Most underrated arcade games?
Beginning in 1970s, 1980s, and 1990s, arcade games were great quarter-poppers until everyone started copying Time Killers, Street Fighter, and car racing games. :-P
A lot of very decent arcade games slipped by the radar - sadly enough - and I'd like to see some folks here mention arcade releases that weren't as popular as you think they deserved to be. Making my list:
Asteroids Deluxe - How did this get so much negative hype? The action was smoother, the control was better, the hit detection was better (allowing you to blast a rock that's right in front of your face), and the array of enemies kept you entertained far longer than the predecessor. This remains one of my all-time favorites.
Ataxx - Okay, I can understand why this one wasn't more popular. It's a turn-based strategy game, and such things are difficult to promote in arcades. And the arcade-going audience isn't really appropriate for a game like this. But for playing it at home, it's a blast.
Gyruss - This one is easy to pick up and play, and if you're into space shooters, it's awesome, especially since it's a shooter of another kind. No idea why this one didn't take off. The graphics of the title screen see a bit dated for the time, though.
Joust 2: Survival Of The Fittest - Setting aside the overused phrase in the title, this game left me little to complain about. The game expands its cast of characters, and allows you to transform your bird into a Pegasus! That's f**king awesome! According to the game designers, the shape of the game's display made it pretty much impossible to port this one to any gaming console, so it couldn't depend on the console ports to spread its popularity around.
Pac-mania - Again, this one got a lot of flak for some reason. Imagine Pac-man with a Zaxxon-like perspective, where the screen scrolls around, and each maze has new music and cut scenes in it. Not only that, but you can jump over enemies. Maybe this one was just too unlike Pac-man for many people, but it suits me just fine.
"Glass Tiger for life!