Most of the time, when I map a game, I'll also rip a lot of sprites for items, enemies, blocks, etc, because they are useful when completing a map.
Sometimes, I'll also rip sprites for personal reason (because I think they look cool) but I never bother doing whole sprite sets. For example, while mapping the NES Mega Man games, I'll rip a Robot Master's starting sprite and those of its attacking pose and its weapons, but I don't capture its taunting animation or all its movements. In short, nothing that I'd be comfortable submitting since it's all very arbitrary.
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Current projects: Metal Storm (NES), Clock Tower (SNES), Ristar-The Shooting Star (Gen), Sonic The Hedgehog (Gen), Sonic CD (Sega CD), Mega Man Zero (GBA), Battletoads (NES), Bucky O'Hare (NES)