Played this game on PS3 when it first launched, I wasn't blown away by it, picked it up just because I wanted to play something similar to Dead Nation. It is a very basic top down space horror themed shooter with bland story told via comic book stile pictures. There is a trilogy but the sequels are the same with remixed levels and different color, first game is blue, second is green and third is yellow. I would suggest playing the other two only if you really like the story otherwise just ignore the sequels.
Swat 2 needs some obscure third party video plugins, GOG should have the courtesy of providing them in the game's files. Swat 1 also has issues with the save files, you need to manually backup the file or it overwrites when you boot the game and sometimes the saving won't register. Have this installed in an older windows vista PC.
