mrcrispy83: off the top of my head the platform games I can think of on gog include but are not limited to
Rayman series
crystal caves
secret agent
realms of chaos
Duke Nukem 1 and 2
unepic
psychonauts
Earthworm Jim
Fez
Giana sisters
rogue legacy
Valdis Story
Volgarr the Viking
Steamworld Dig
Guacamelee
Mutant Mudds (though the GOG version is pretty far behind every other version IIRC)
superfrog
Escape Goat
Hocus Pocus
Dustforce
Pandemonium
Adventures of Shuggy
Blocks that Matter and Tetrobot co
Shovel Knight
Dangerous Dave
well that should be enough to look in for for starters, there's probably a platformer gogmix too if you skim through them