I had no idea one of these existed. I've seen the KEEN6.COM loader to disable the creature question, but never something like this: infinite ammo and infinite lives.
It's included in The Old Computer's copy of Keen 6. (Google it. I'm still slightly wary of linking to these kind of things. KeenRush's vendetta hasn't completely abated. ) Anyway keen6tr.com in the file, haven't seen something like this before, check it out if you want.
My original copy of Keen 6 was run via a similar trainer. Wasn't this one though, as it had a colourful ASCII art screen that made sure you knew who made it. Think it took a couple of years before I finally got the chance to play Keen 6 without the unlimited lives and ammo. Boy was I disappointed to see a plain 'Game Over' window instead of Bloogs eating Molly.