This is a fun game! What starts as a tense puzzler ends in a explosion-loaded boss fight! Works for me!
If you're looking for more puzzles, try Research and Development (Here's what it looks like)
If you're looking for more shooting, try Entropy: Zero (Half the mod is showcased here)
I can personally recommend each of these three mods as short (1-4 hour) endorphin-tickling good times.