<s>
This	O
is	O
a	O
list	O
of	O
some	O
of	O
the	O
most	O
popular	O
freeware	B-License
and	O
free	B-License
and	I-License
open-source	I-License
software	I-License
first-person	O
shooter	O
games	O
.	O
</s>
<s>
Title	O
Developer	O
Release	O
date	O
Last	O
update	O
Operating	B-General_Concept
system	I-General_Concept
Engine	O
License	B-License
NotesAction	O
Quake	B-Application
2	I-Application
The	O
Action	O
Team	O
1998	O
2003	O
Linux	B-Application
,	O
Windows	B-Application
id	B-Application
Tech	I-Application
2	I-Application
Freeware	B-License
Team	O
and	O
Deathmatch	O
based	O
very	O
fast	O
FPSAssaultCube	O
Rabid	O
Viper	O
Productions	O
2006	O
2022-04-01	O
(	O
1.3.0.2	O
)	O
Linux	B-Application
,	O
Mac	B-Application
OS	I-Application
,	O
Windows	B-Application
,	O
Android	B-Application
Cube	B-Application
Engine	I-Application
zlib	B-License
License	I-License
(	O
code	O
)	O
,	O
Individual	O
licenses	O
(	O
media	O
)	O
Realistic	O
environments	O
,	O
fast	O
arcade	O
game	O
play	O
,	O
many	O
game	O
modes	O
.	O
</s>
<s>
Single/Multiplayer.AssaultCube	O
Reloaded	O
(	O
ACR	O
)	O
AssaultCube	B-Application
Reloaded	O
Task	O
Force	O
2010	O
2021	O
Linux	B-Application
,	O
Mac	B-Application
OS	I-Application
(	O
requires	O
manual	O
compilation	O
)	O
,	O
Windows	B-Application
Improves	O
AssaultCube	B-Application
.	O
</s>
<s>
Single/Multiplayer.Black	O
Shades	O
Wolfire	O
games	O
2001	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
,	O
Mac	B-Application
OS	I-Application
,	O
iOS	B-Application
Wolfire	O
Games	O
Freeware	B-License
Free	O
First-person	O
shooterBZFlag	O
Chris	O
Schoeneman	O
,	O
Tim	O
Riker	O
1993	O
2022-03-08	O
(	O
2.4.24	O
)	O
Linux	B-Application
,	O
BSD	B-Operating_System
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
,	O
other	O
UNIX	B-Application
GNU	B-Application
LGPL	I-Application
Tank	O
combatChub	O
Gam	O
3D	O
:	O
Director	O
's	O
Cut	O
ChubGamSoft	O
1998	O
MS-DOS	B-Application
Pie	B-Application
in	I-Application
the	I-Application
Sky	I-Application
Freeware	B-License
Surreal	O
horror	O
single	O
player	O
gameCodeRED	O
:	O
Alien	B-Application
Arena	I-Application
COR	B-Application
Entertainment	I-Application
,	O
LLC	O
2004-11	O
2011-12-29	O
(	O
7.53	O
)	O
Linux	B-Application
,	O
BSD	B-Operating_System
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
CRX	O
Engine	O
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
media	O
)	O
Science	O
fiction	O
,	O
with	O
single	O
or	O
multiplayer	O
modes.CubeWouter	O
van	O
Oortmerssen20012005-08-29Linux	O
,	O
BSD	B-Operating_System
,	O
Mac	B-Application
OS	I-Application
,	O
WindowsCube	O
Enginezlib	O
License	B-License
(	O
code	O
)	O
,	O
Individual	O
licenses	O
(	O
media	O
)	O
Quake	B-Application
style	O
multiplayer	O
deathmatch	O
.	O
</s>
<s>
Single/Multiplayer.Cube	O
2	O
:	O
Sauerbraten	O
Wouter	O
van	O
Oortmerssen	O
2004	O
2020-11-30	O
Linux	B-Application
,	O
BSD	B-Operating_System
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
Cube	B-Application
2	I-Application
Engine	I-Application
zlib	B-License
License	I-License
(	O
code	O
)	O
,	O
Individual	O
licenses	O
(	O
media	O
)	O
Quake	B-Application
style	O
deathmatch	O
,	O
includes	O
built	O
in	O
level	O
editor	O
.	O
</s>
<s>
Single/Multiplayer.The	O
Dark	O
Mod	O
Team	O
Dark	O
Mod	O
2009	O
2015-02-08	O
(	O
2.03	O
)	O
Windows	B-Application
id	B-Application
Tech	I-Application
4	I-Application
engine	O
CC-BY-NC-SA	O
First	O
person	O
stealth	O
game	O
in	O
the	O
style	O
of	O
the	O
Thief	B-Application
series	O
games	O
(	O
1	O
and	O
2	O
)	O
using	O
a	O
modified	O
Id	B-Application
Tech	I-Application
4	I-Application
engineFallen	O
Empire	O
:	O
Legions	O
GarageGames	O
,	O
InstantAction	O
2009-06-30	O
2013-06-27	O
Windows	B-Application
Torque	B-Application
Game	I-Application
Engine	I-Application
Proprietary	B-Application
license	I-Application
First-Person	O
Shooter	O
with	O
Jetpacks	O
,	O
Multiplayer	O
,	O
CTF	O
,	O
DeathmatchFreedoom	O
Freedoom	O
project	O
2019-10-22	O
(	O
0.12.1	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
,	O
Android	B-Application
,	O
Mac	B-Application
OS	I-Application
,	O
MS-DOS	B-Application
,	O
others	O
Doom	B-Application
engine	I-Application
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
BSD	B-Operating_System
(	O
media	O
)	O
A	O
Doom	B-General_Concept
WAD	I-General_Concept
file	O
intended	O
to	O
be	O
used	O
instead	O
of	O
the	O
copyrighted	O
file	O
from	O
the	O
original	O
Doom	O
and	O
Doom	O
II.The	O
Glorious	O
Mission	O
Giant	O
Interactive	O
Group	O
2013-06-20	O
Windows	B-Application
Proprietary	B-Application
license	I-Application
Online	O
multiplayer	O
.	O
</s>
<s>
Developed	O
with	O
the	O
People	O
's	O
Liberation	O
Army	O
of	O
China	O
for	O
use	O
as	O
a	O
recruitment	O
and	O
training	O
tool.Gore	O
:	O
Special	O
Edition	O
4D	O
Rulers	O
2008-07-04	O
Windows	B-Application
AMP	O
engine	O
Proprietary	B-Application
licenseHidden	O
&	O
Dangerous	O
Illusion	O
Softworks	O
,	O
Take-Two	O
Interactive	O
1999-07-29	O
2001-11	O
Windows	B-Application
Insanity	O
Engine	O
Proprietary	B-Application
license.kkrieger	O
.theprodukkt	O
2004	O
Windows	B-Application
Proprietary	B-Application
license	I-Application
Won	O
first	O
place	O
in	O
the	O
96k	O
game	O
competition	O
at	O
Breakpoint	O
in	O
April	O
2004.Kuma	O
\War	O
Kuma	O
Reality	O
Games	O
2004	O
2006-07	O
Windows	B-Application
Source	B-Application
engine	I-Application
Proprietary	B-Application
license	I-Application
Tactical	O
episodic	O
shooter	O
.	O
</s>
<s>
Single/Multiplayer.Marathon	O
Bungie	O
1994-12-21	O
2007	O
Mac	B-Application
OS	I-Application
(	O
original	O
)	O
,	O
ported	O
to	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
and	O
Windows	B-Application
via	O
AlephOne	O
Aleph	O
One	O
GNU	B-License
GPL	I-License
(	O
code	O
)	O
Released	O
as	O
freeware	B-License
and	O
source	B-Application
code.Nexuiz	O
Alientrap	O
2005-05-31	O
2009-10-01	O
(	O
2.5.2	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
(	O
10.4	O
or	O
later	O
)	O
,	O
Windows	B-Application
DarkPlaces	O
Quake	B-Application
engine	I-Application
GNU	B-License
GPL	I-License
Unreal	B-Operating_System
Tournament	I-Operating_System
style	O
deathmatch	O
.	O
</s>
<s>
Single/Multiplayer.OpenArena	O
OpenArena	B-Application
team	O
2005-08-19	O
2012-02-20	O
(	O
0.8.8	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
ioquake3	B-Application
id	B-Application
Tech	I-Application
3	I-Application
GNU	B-License
GPL	I-License
Free	O
software	O
content	O
remake	O
of	O
Quake	B-Application
III	I-Application
Arena	I-Application
.	O
</s>
<s>
Single/MultiplayerOpenSpadesYVT2019	O
-01-04	O
(	O
0.1.3	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
WindowsGNU	O
GPLBased	O
on	O
Ace	O
of	O
Spades	O
0.75Point	O
Blank	O
Zepetto	O
,	O
NCSOFT	O
2008-03	O
Windows	B-Application
N/A	O
Proprietary	B-Application
license	I-Application
Free	O
FPS	O
created	O
by	O
Zepetto	O
in	O
2009	O
.	O
</s>
<s>
Red	B-Application
Eclipse	I-Application
Quinton	O
Reeves	O
,	O
Lee	O
Salzman	O
2011-03-15	O
2019-12-19	O
(	O
2.0.0	O
)	O
Linux	B-Application
,	O
BSD	B-Operating_System
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
Cube	B-Application
2	I-Application
Engine	I-Application
/	O
Tesseract	O
zlib	B-License
License	I-License
New	O
take	O
on	O
the	O
first	O
person	O
arena	O
shooter	O
,	O
featuring	O
parkour	O
,	O
impulse	O
boosts	O
,	O
and	O
more.S.T.A.L.K.E.R.	O
</s>
<s>
build	O
1935	O
GSC	O
Game	O
World	O
2009-02	O
Windows	B-Application
xrCore	O
build	O
1935	O
Proprietary	B-Application
license	I-Application
2004	O
Alpha	O
build	O
of	O
S.T.A.L.K.E.R.	O
</s>
<s>
:	O
Shadow	B-Application
of	I-Application
Chernobyl	I-Application
.	O
</s>
<s>
Has	O
a	O
number	O
of	O
bugs	O
but	O
contains	O
a	O
full	O
,	O
playable	O
single	O
player	O
campaign.Savage	O
:	O
The	O
Battle	O
for	O
Newerth	O
S2	O
Games	O
2003-09-09	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
(	O
commercial	O
)	O
,	O
Windows	B-Application
Silverback	O
Engine	O
Proprietary	B-Application
license	I-Application
Hybrid	O
FPS/RTS	O
with	O
both	O
ranged	O
and	O
melee	O
combatSavage	O
2	O
:	O
A	O
Tortured	O
Soul	O
S2	O
Games	O
2008-01-16	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
(	O
commercial	O
)	O
K2	O
Engine	O
Proprietary	B-Application
license	I-Application
The	O
sequel	O
to	O
the	O
award-winning	O
game	O
,	O
Savage	O
:	O
The	O
Battle	O
for	O
Newerth.Smokin	O
'	O
Guns	O
Smokin	B-Application
 '	I-Application
Guns	I-Application
Productions	O
and	O
Iron	O
Claw	O
Interactive	O
2009-01-01	O
2012-06-08	O
Linux	B-Application
,	O
BSD	B-Operating_System
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
,	O
others	O
ioquake3	B-Application
id	B-Application
Tech	I-Application
3	I-Application
GNU	B-License
GPL	I-License
(	O
code/some	O
media	O
)	O
Proprietary	B-Application
license	I-Application
(	O
some	O
media	O
)	O
Western	O
Quake-like	O
FPS	O
.	O
</s>
<s>
Single	O
(	O
with	O
bots	O
)	O
/Multiplayer.Starsiege	O
:	O
Tribes	O
Dynamix	O
,	O
Sierra	O
Entertainment	O
2004	O
(	O
free	O
release	O
)	O
Windows	B-Application
Darkstar	O
engine	O
Proprietary	B-Application
license	I-Application
Futuristic	O
team	O
based	O
combat	O
,	O
released	O
for	O
free	O
to	O
promote	O
Tribes	B-Application
:	I-Application
Vengeance	I-Application
.	O
</s>
<s>
Multiplayer	O
only.The	O
DinoHunters	O
Kuma	O
Games	O
2006-04-24	O
Windows	B-Application
Source	B-Application
engine	I-Application
Proprietary	B-Application
license	I-Application
Also	O
a	O
machinima	O
series	O
.	O
</s>
<s>
Single/Multiplayer.Tremulous	O
Dark	O
Legion	O
Development	O
2006-03-31	O
2009-12-04	O
(	O
preview	O
release	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
(	O
unofficial	O
)	O
,	O
Windows	B-Application
ioquake3	B-Application
id	B-Application
Tech	I-Application
3	I-Application
GNU	B-License
GPL	I-License
Aliens	O
vs	O
Humans	O
multiplayer	O
team	O
combat	O
with	O
some	O
RTS	O
elements.Tribes	O
2	O
Dynamix	O
,	O
Sierra	O
Entertainment	O
2004	O
(	O
free	O
release	O
)	O
Windows	B-Application
Torque	B-Application
Game	I-Application
Engine	I-Application
Proprietary	B-Application
License	I-Application
Futuristic	O
team	O
based	O
combat	O
,	O
released	O
for	O
free	O
to	O
promote	O
Tribes	B-Application
:	I-Application
Vengeance	I-Application
.	O
</s>
<s>
Single/Multiplayer.UberStrike	O
Cmune	O
2010-09-17	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
Unity	B-Application
Proprietary	B-Application
license	I-Application
Free-to-play	O
"	O
social	O
shooter	O
"	O
on	O
Facebook	O
,	O
MySpace	O
and	O
Apple	O
's	O
Dashboard	O
Widgets.Unreal	O
TournamentEpic	O
GamesTBA2015-03-09Linux	O
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
WindowsUnreal	O
Engine	O
4Proprietary	O
licenseCrowdsourced	O
and	O
free	O
first-person	O
shooter.UnvanquishedUnvanquished	O
Unvanquished	B-Application
Development	O
2012-02-29	O
2021-06-21	O
(	O
Alpha	O
0.52.1	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
modified	O
ioquake3	B-Application
CC	O
BY-SA	O
2.5/GPL	O
Fork	O
of	O
Tremulous	B-Application
with	O
new	O
assetsUrban	O
Terror	O
Silicon	O
Ice	O
Development	O
/	O
Frozen	O
Sand	O
2000-08-05	O
(	O
Beta	O
1.0	O
)	O
2018-06-21	O
(	O
4.3.4	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
ioquake3	B-Application
id	B-Application
Tech	I-Application
3	I-Application
GNU	B-License
GPL	I-License
(	O
ioquake3	B-Application
engine	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
mod	O
code	O
,	O
media	O
)	O
Fast-paced	O
,	O
Hollywood	O
tactical	O
shooter	O
.	O
</s>
<s>
Originally	O
a	O
Quake	B-Application
3	I-Application
mod	O
,	O
now	O
a	O
standalone	O
game.Warmonger	O
:	O
Operation	O
Downtown	O
Destruction	O
NetDevil	O
2007-11-28	O
2009-08-27	O
Windows	B-Application
Unreal	B-Operating_System
Engine	I-Operating_System
3	O
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
media	O
)	O
High-end	O
Free-to-play	O
first	O
person	O
shooter	O
with	O
destructible	O
environments	O
..	O
Warsow	B-Application
Warsow	B-Application
team	O
2005-06-08	O
2016-04-14	O
(	O
2.1	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
Qfusion	B-Language
id	B-Application
Tech	I-Application
2	I-Application
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
media	O
)	O
Quake	B-Application
style	O
deathmatch	O
focussed	O
on	O
high-paced	O
action	O
and	O
trickjumps.Wolfenstein	O
:	O
Enemy	O
Territory	O
Activision	O
,	O
id	O
Software	O
,	O
Splash	O
Damage	O
2003-05-29	O
2015-08-21	O
(	O
ET:Legacy	O
2.74	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
id	B-Application
Tech	I-Application
3	I-Application
,	O
ET:Legacy	O
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
media	O
)	O
Intended	O
expansion	O
pack	O
turned	O
freeware	B-License
.	O
</s>
<s>
WW2	O
multiplayer	O
team	O
combatWorld	O
of	O
Padman	O
Padworld	O
Entertainment	O
2007-04-01	O
2011-07-16	O
(	O
1.5.4	O
beta	O
Windows/Linux	O
)	O
,	O
2011-01-24	O
(	O
1.5.1	O
OS	B-Operating_System
X	I-Operating_System
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
ioquake3	B-Application
id	B-Application
Tech	I-Application
3	I-Application
GNU	B-License
GPL	I-License
(	O
code	O
)	O
,	O
Proprietary	B-Application
license	I-Application
(	O
media	O
)	O
A	O
free	O
Quake	B-Application
3	I-Application
like	O
comical	O
FPS	O
gameXonotic	O
Team	O
Xonotic	B-Application
2010-12-23	O
2022-06-30	O
(	O
0.8.5	O
)	O
Linux	B-Application
,	O
OS	B-Operating_System
X	I-Operating_System
,	O
Windows	B-Application
DarkPlaces	O
Quake	B-Application
engine	I-Application
GNU	B-License
GPL	I-License
Fork	O
and	O
direct	O
successor	O
of	O
the	O
Nexuiz	B-Application
Project.Team	O
Fortress	O
2Valve2007-10-72019-3-28Windows	O
,	O
Mac	B-Application
OS	I-Application
,	O
Linux.Source	O
Proprietary	B-Application
licenseAlso	O
available	O
on	O
Xbox	B-Operating_System
360	I-Operating_System
and	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
formerly	O
pay	O
to	O
play	O
,	O
sequel	O
to	O
Team	B-Application
Fortress	I-Application
Classic	I-Application
.	O
</s>
<s>
Some	O
free-to-play	O
online	O
first-person	O
shooters	O
use	O
a	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
,	O
in	O
which	O
only	O
the	O
client	O
is	O
available	O
for	O
free	O
.	O
</s>
<s>
Title	O
Developer	O
,	O
Publisher	O
Release	O
date	O
Operating	B-General_Concept
system	I-General_Concept
Engine	O
License	B-License
Notes	O
Blacklight	B-Application
:	I-Application
Retribution	I-Application
Zombie	O
Studios	O
2012-04-03	O
Windows	B-Application
Unreal	B-Operating_System
Engine	I-Operating_System
3	O
Proprietary	B-Application
license	I-Application
Online	O
multiplayer	O
,	O
futuristic	O
setting.Crossfire	O
Z8Games	B-Application
2006	O
Windows	B-Application
Lithtech	B-Application
Jupiter	O
Freeware	B-License
Modern	O
team-based	O
shooter	O
.	O
</s>
<s>
Many	O
game	O
modes.Mission	O
Against	O
Terror	O
Kingsoft	O
Dalian	O
JingCai	O
Studio	O
,	O
Wicked	O
Interactive	O
/	O
Suba	O
Games	O
2012	O
Windows	B-Application
Proprietary	B-Application
license	I-Application
Free-to-play	O
online	O
fps	O
,	O
developed	O
by	O
KingSoft	O
,	O
published	O
by	O
Wicked	O
Interactive	O
/	O
Suba	O
Games	O
.	O
</s>
<s>
Fallen	B-Protocol
Earth	I-Protocol
?	O
</s>
<s>
Online	O
multiplayerList	O
of	O
free	O
MMOFPS	O
games	O
Heroes	B-Application
and	I-Application
Generals	I-Application
?	O
</s>
<s>
Online	O
multiplayer	O
War	B-Application
Rock	I-Application
?	O
</s>
<s>
Online	O
multiplayer	O
,	O
features	O
controllable	O
vehicles	O
Combat	B-Application
Arms	I-Application
Nexon	O
2008-07-11	O
Windows	B-Application
Lithtech	B-Application
Proprietary	B-Application
license	I-Application
Online	O
multiplayer	O
,	O
modern	O
setting	O
;	O
microtransaction	O
business	O
model	O
.	O
</s>
<s>
CrimeCraft	B-Protocol
Vogster	O
Entertainment	O
2009-08	O
Windows	B-Application
Unreal	B-Operating_System
Engine	I-Operating_System
3	O
Proprietary	B-Application
license	I-Application
Massively	O
multiplayer	O
online	O
with	O
3rd	O
and	O
1st-person	O
perspectives	O
;	O
microtransaction	O
business	O
model	O
.	O
</s>
<s>
PlanetSide	B-Protocol
2	I-Protocol
Daybreak	O
Game	O
Company	O
2012-11-20	O
Windows	B-Application
ForgeLight	O
Proprietary	B-Application
license	I-Application
Massive	O
battles	O
with	O
2000	O
players	O
per	O
continent	O
at	O
a	O
time	O
.	O
</s>
<s>
Sudden	B-Application
Attack	I-Application
Nexon	O
2005-4-11	O
Windows	B-Application
Lithtech	B-Application
Proprietary	B-Application
license	I-Application
Online	O
multiplayerTribes	O
:	O
Ascend	O
Hi-Rez	O
Studios	O
2011-12	O
Windows	B-Application
Unreal	B-Operating_System
Engine	I-Operating_System
3	O
(	O
modified	O
)	O
Proprietary	B-Application
license	I-Application
Online	O
multiplayer	O
;	O
microtransaction	O
business	O
model	O
.	O
</s>
<s>
EngineDeveloper	O
,	O
PublisherRelease	O
dateLinuxOS	O
XWindowsotherLicenseNotes	O
Aleph	O
One	O
Bungie	O
(	O
originally	O
)	O
2000-01-17	O
Mac	B-Application
OS	I-Application
,	O
BSDs	B-Operating_System
GPL-3.0-or-later	B-License
Aleph	O
One	O
is	O
an	O
open-source	O
project	O
based	O
on	O
the	O
Marathon	B-Application
2	I-Application
:	I-Application
Durandal	I-Application
code	O
,	O
which	O
was	O
released	O
to	O
the	O
public	O
by	O
Bungie	O
.	O
</s>
<s>
Build	B-Application
engine	I-Application
Ken	O
Silverman/3D	O
Realms	O
2000-06-20	O
Custom	O
licence	O
,	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
First	O
released	O
by	O
Silverman	O
;	O
3D	O
Realms	O
later	O
did	O
GPL	B-License
releases	O
of	O
Duke	B-Application
Nukem	I-Application
3D	I-Application
and	O
Shadow	B-Application
Warrior	I-Application
Cube	B-Application
Engine	I-Application
Wouter	O
van	O
Oortmerssen	O
2001	O
Android	B-Application
zlib	B-License
License	I-License
(	O
code	O
)	O
,	O
Individual	O
licenses	O
(	O
media	O
)	O
FPS	O
with	O
sandbox	O
style	O
level-editor	O
Cube	B-Application
2	I-Application
Engine	I-Application
Wouter	O
van	O
Oortmerssen	O
2004	O
zlib	B-License
License	I-License
(	O
code	O
)	O
,	O
Individual	O
licenses	O
(	O
media	O
)	O
FPS	O
with	O
sandbox	O
style	O
level-editor	O
Dim3	B-Operating_System
Brian	O
Barnes	O
MIT	B-License
License	I-License
Development	O
set	O
id	O
Tech	O
0	O
id	O
Software	O
1995	O
GPL-2.0-or-later	B-License
Wolfenstein	B-Application
3D	I-Application
.	O
</s>
<s>
Also	O
available	O
from	O
Blake	B-Application
Stone	I-Application
:	I-Application
Planet	I-Application
Strike	I-Application
source	B-Application
release	O
;	O
earlier	O
versions	O
in	O
Hovertank	B-Application
3D	I-Application
and	O
Catacomb	B-Application
3-D	I-Application
source	B-Application
releases	O
,	O
and	O
further	O
developed	O
in	O
Rise	B-Application
of	I-Application
the	I-Application
Triad	I-Application
source	B-Application
release	O
id	B-Application
Tech	I-Application
1	I-Application
id	O
Software	O
1999-10-03	O
GPL-2.0-or-later	B-License
Known	O
as	O
the	O
Doom	B-Application
engine	I-Application
,	O
originally	O
used	O
for	O
Doom	O
,	O
Doom	O
II	O
,	O
and	O
clones	O
.	O
</s>
<s>
id	B-Application
Tech	I-Application
2	I-Application
id	O
Software	O
1999-12-21	O
GPL-2.0-or-later	B-License
Quake	B-Application
,	O
Hexen	O
II	O
,	O
DarkPlaces	O
is	O
an	O
open	O
source	B-Application
derivative	O
.	O
</s>
