I've tanked so much time in Zombie Master (a Source mod)... the community is very lively for a mod that's developement team disbanded almost two years ago.
EDIT: I've been trying for fucking ages to get a Source mod called Underhell to work.
First, it worked fine until I used a flashlight. EARRAPE. Then the game crashed.
Deleted, reinstalled from the same .RAR file. Better, but the game still crashed, subtitles were missing characters, and sometimes the earrape would randomly happen.
Deleted it again, redownloaded it. Worked PERFECTLY... until, around halfway through the tutorial, the game crashed.
Delete. Redownloaded the .exe file instead of the .rar file. Worked fine, but again the flashlight was utter earrape and characters were missing from everywhere... the subtitles, the menu, the options, even the "Exit Game" button.
Delete. Redownload. Run .exe file. IMMEDIATELY the file doesn't respond, and upon closing it my computer freezes, only displaying the background. Reboot works fine.
No matter how many times I run the same .exe file, the same bloody thing happens.
But, Jesus, I want to play it -- the people who made Nightmare House 2 helped with production, the music is awesome, the gameplay reminded me heavily of a combination Heavy Rain and SWAT 4, and it uses the SMOD Engine, and I fucking love SMOD.