Helium is a set of open-source cross-platform C++ Frameworks, and it aspires to be a high performance Game Engine. It is permissively licensed under a BSD-style license.
Platform is a simple platform abstraction layer that works on Windows, OSX, and Linux. It provides a thin abstraction layer to file i/o, threads, synchronization primitives, and address space allocation.
Foundation is a set of C++ containers, interprocess communication, reference counting, and language utilities like events and delegates.
Reflect is an implementation of C++ reflection that provides metadata that can help automate many rote programming tasks.
Persist is an implementation of object persistence that utilizes C++ reflection. It currently supports JSON and BSON, and it can handle both data within an object as well as relationships between objects (potentially stored in separate files).
Mongo is an implementation of the database object model pattern that uses C++ reflection for marshaling object data to and from mongodb.
Right now the Game Engine is under heavy development. We are building an engine and tool set that is heavily based around Components and Introspection. We aim to build a high performance engine that exposes internal state to the user as much a possible via a WYSIWYG editor.