Yeah, some sort of manual, if only a small text file, would have been nice, since some of the commands are not readily apparent. For the time being, I suggest looking up GameFAQs for information on the arcade versions of these games.

dd2 biggest discrepency, standard kicks are to defend your back, kinda like renegade for the NES.

the jumping spin kick from the first game (jump + kick) is replaced with more of a forward spinning heel kick, propels you forward.

running is now a factor, & like the NES version you can do the tornado levitating kick, if you time it @ the very apex of the jump, standing or running. dont think the hyper uppercuts from the nes port are there, i could be wrong though.

i did a standing knee strike. i have no idea how that happened, unless its like the uppercut or standing spin kick, from a stunned enemy combo, in dd1.

idk much about rosetta stone, other then it looks & plays like a hot mess.

you can run, pressing jump + punch & you do an inverted handstand on their heads, head butt them from above. rather bizarre.

running towards a downed enemy & pressing punch & you'll do a flying knee drop. run + punch normal = a flying clothesline. jump + kick = tornado levitate kick, like dd2.

the over the shoulder throw has been replaced by a final fight - like suplex, performed from behind though.

i agree some documentation would be nice but i dont blame gog so much as whoever rebooted & compiled these.