There are a lot of unique console games that work extremely well on a 2-player upright. Not all console games are 1-player lengthy password-save text-ridden rpgs. Frequented 2 player simultaneous games at my house for the last decade with the kids are...
Twisted Metal 2 (psx). If you have 6 buttons this is very playable, and fun in co-op mode.
The Unholy War (psx). Kind of an updated Archon.
Streets of Rage 2, Toe Jam n Earl, Zombies Ate my Neighbors (Genesis)
Gunfight, Freeway, Frogs n Flies, Combat, Fishing Derby (Atari 2600)
Dogdaze Deluxe, Seawolf 2, Archon, Beachhead 2, International Karate, Match wits (Atari 800)
Pro Wrestling (NES)