Commander Genius - an open source port for Commander Keen 1 through 6.

It includes features like:

• Mod Support with some extras using Lua
• OpenGL Acceleration
• SDL 2.0 Support
• New graphical effects
• Multiplayer Support (Up to four players)
• High Quality Packs which make the game look better, provide better sounds and even music you might never have known existed in the original games
• In-game Menu for Vorticons Keen as well as a new HUD
• Named save slots
• Unrestricted Joystick Support

and much more