Ok, everyone always wants a list of the 10 or 20 or 100 or whatever most influential games, but what about the least? Games that came and went without so much as a flicker. They're not bad games (if they were they usually hurt the developer, ergo they have influence). The difficulty is, you can usually find something they influenced.

Take Weaponlord. Really, really mediocre fighting game. No sequels. Looked about the same on Sega & Nintendo so no fuel for that war. But then again it was Namco's first weapon based fighter. Namco... makers of Soul Calibre, one of the last fighting game franchises alive and well today . The story goes this is what got them interested in weapon based fighters.

I'd say to qualify it'd have to be intended as a proper release for the console or computer, e.g. from a software company (instead of some guys basement) with a bit of a budget. The only exception would be if you're going so far back that such things didn't exists, but then again, everything was influential then; it was a totally new medium.

Here's a few for people to shoot holes in.

Whomp 'Em on the NES
Arrow Flash Sega Genesis
Roland's Curse for Gameboy