2007 to 2010
I have an incredibly odd obsession with Sonic Robo Blast 2, a Sonic the Hedgehog fan game created with one of the Doom engine source ports. SRB2 is by far the best interpretation of classic Genesis Sonic in 3D. During the time when I played the game heavily, I created several custom levels for it. This was my first introduction to game development in 3D (of sorts, since the Doom engine is technically not fully 3D). The SRB2 community hosts a level design contest that I had won twice under the alias 'ComRante'; first with a lush multiplayer capture the flag map and second with a desert-themed single player stage. These stages can be found on the SRB2 forums and the SRB2 wiki.
Credit: SRB2 Game and Development Tools Created by Sonic Team Junior. Check out their great work at the SRB2 Website.