5-Minute First Person Shooter (a free* idea)

I love playing games that involve lots of fast & furious blood-letting. But these days I never have more than 5 or 10 minutes to play games. That's enough to get it out of my system, but games these days are too long-winded!!

How about a game for adults like me (from the first generation of video-gaming teenagers), that does the following in less than 10 minutes:

Although it is just 10 minutes from A to B, how about having an endless variety of bad guys, obstacles, weapons, backgrounds. So sometimes when you play it is just one super nasty to kill, and another time 500 rats. Sometimes you get a rocket launcher, other times just a rolled-up newspaper. Loud, fun killing!

* All I ask for is acknowledgement that I thought of it. I'll never get around the realising them myself, so go for it!
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