We're not old mate, we're fossils... I'm not exactly sure why but that sounded comforting in my head...
Anyway, for a template and a first try your game looks pretty good, and since it's a simply style/concept it's pretty easy to expand. You could have the player go to another part of the level if he leaves the screen, you could have sub-levels behind some of those doors that tie in to the main level, maybe add some elevators that transport you around more easily then the stairs but they olso attract the guards when you use them, etc.
LOL. Fossils, eh? Well, we can salvage some more comfort and recall that fossils can contain some interesting information.
I have several ideas for where to go with the game's core mechanic. One of my future mini projects is to figure out how to get the doors to randomly house one of the items when the level loads so you're guaranteed to play a different version of the game (given permutation limits, of course). The elevator idea never occurred to me, but I think one of my game ideas could use that. Nice!
Thanks for the review and the suggestions!