PICO-8 - Lua-based fantasy console for making and playing tiny, computer games and programs.
Godot Engine - Feature-packed 2D and 3D open source game engine.
TIC-80 - TIC-80 is a fantasy computer where you can make, play and share tiny games.
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
Pyxel - Retro game engine for Python inspired by fantasy consoles.
BYOND - BYOND is the premier community for making and playing online multiplayer games.