Ah, Good old Lemmings,
one of the first games I owned, way back on the Amiga 500 for those who remember them.
The game is an excellent adaptation, the premise is the same as the original, guide the lemmings from the trapdoor to the exit using a variety of skills to manipulate the environment. The game is split into four categories of 30 levels each, Fun, Tricky, Taxing and Mayhem. As expected, the difficulty level increase as you advance. Fun is a relatively easy first jaunt out to familiarise yourself with how the game works and the different skills, Mayhem is where it really gets off the wall, I challenge you to complete it :)!!.
The PSP version includes a new fifth category of special levels for PSP, and there is an editor so you can create your own and release them on the interweb.
I did notice that some of the more expansive levels (about two out of each category) have been cut back a little, probably due to memory constraints or something, and the time limits have been altered to be more forgiving than the original Amiga version, but other than that it is a faithful recreation.
its a welcome trip down memory lane for older players, and a fresh exciting challenge for new ones, "lets go..."