DarkBASIC has a simpler syntax. It's basically easier.
People say it has really bad bugs but I've never come across any, the rotation system is a bit hard to understand (BUT IT DOES WORK PROPERLY). EZRotate is free and sorts this out.
DBPro runs DX 9, B3D runs DX 8.1 so it can't do the better shaders etc. Won't really affect most people though.
Check all of these out:
I world - GTA like game
Newton - Amazing Physics
Open source community FPS
Unnamed - Space RTS
Firewall - Very nice RTS
Suncrusher - Really nice space game
Super Tito - Really good cartoony 3d platform game
I couldn't find links for
Duo
Roomwar
Operation Invasion Evasion
Roswell Racer
They're all great as well.
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Tankoids - 2D worms-like game (written by a genius)