METAL SLUG ADVANCE / Snk / Gameboy Advance
Metal Slug Advance attempts to fuse a port of the arcade gameplay with the Pokemon-esque "collectamania" that Nintendo handhelds are known for. It only sort of works out.
This really is a pretty interesting adaptation of the arcade games. There's a break between each level to go to a map screen, and you can replay previous levels to try to get higher rankings. Each level also has a set amount of cards and prisoners, and whatever you complete the level with gets added to a sort of Pokedex of both for your obsessive-compulsive viewing pleasure.
Graphically, the game is extremely solid, not that far off from the high-powered visuals of the arcade games - no mean feat for the GBA. Don't expect any massive boss enemies or jaw-dropping sequences, but the enemies retain their suite of detailed and comical animations without losing much in the way of frames. The classic sound effects such as "Rocket Lounger!" also make the jump over as well.
The main problem with the game is that it's just a bit too hard - get stuck on a level and there's nothing else to do but sit there and be stuck, or replay previous levels to find all the hidden stuff. Eventually you can adapt and overcome if you have the patience, but the "collecting" aspect is pretty weak too - some of the cards you find unlock bonus stuff and cheats, but the prisoners just give you a list of names that aren't even clever or creative really.
When they sat down to plan how to tweak and add bonus stuff to this handheld game, why didn't anyone bring up fixing the series greatest weakness to date - the inability to shoot diagonally? Why not allow players to stock more than one special weapon and switch them out mid-game - there's literally 3 buttons not being used during gameplay! And why would you not incorporate a 2-player mode, when that is the greater part of the appeal of the arcade games?