I even like the fact that it still uses 90 degree walls. It makes building levels quick and easy - like building with Lego.
The music is excellent. I much prefer it over the PC Doom music.
The graphics are nice and I really like the palette. The only thing I would've liked is a little more variation in the looks of the enemies. They all look a bit too similar from a distance. Stronger physical identities would make a big difference...
I really wish there was a stable and maintained source port and editor. The game needs more love...
