So, I just got MAME because I wanted to play Rolling Thunder... I have it on the Xbox Namco collection but I didn't feel like dragging out another console. And it works perfectly, with my Xbox 360 controller no less. So I figured, hey, let's take a look at what else is out there.

I find that there are tons of foreign vertical scrolling shooters (one of my all-time favorite types of games) that work with the emulator. Just tried ESP Ra.De. - absolutely incredible. I don't even know of another way to ever even have the chance to play this game, but thanks to MAME I can. Unfortunately it seems like Radiant Silvergun has some issues, but thankfully that should be coming out on the consoles soon.

What are your favorite arcade games? Are there any that I absolutely need to play?

If you like vertical side scrollers, you have to look into the Strikers 1945 series, and other games by Psikyo, like Gunbird. No complex mechanics, no gimmicks - just 16 stages of testing your reflexes and coordination. Sure you can watch a walkthrough on Youtube, but there wouldn't be any fun in that.

The Strikers series I managed to beat all 3 of them up till 2-1 (Level 2, Stage 1, which is the equivalent of Stage 9); I get my ass handed back to me after that.

Sonic Wings - Aero Fighters 1, 2 and 3 are a must.

That and 19XX the War Against Destiny.

ENJOY BRO!

These are good too. Old but pretty good. I believe Psikyo got its inspiration in the first Striker from Aero Fighters 1, but that's just a wild hunch.

Awesome recommendations guys, I just played a couple minutes of Strikers and Sonic Wings, both beautiful and awesome. And 19XX is great too, parachuting tanks! I'm definitely going to be playing these for the foreseeable future...

I should also mention that the controls in Strikers 1 are a bit clumsy. Strikers 2 refines it, and is IMO the best WWII-themed vertical scroller. You can't go wrong with the Flying Pancake.

Ghosts'n Goblins - Ghouls'n Ghosts
Final Fight
Street Fighter EX
Fighting Layer
Black Tiger
Commando
Section Z
Strider - Strider 2
Wonderboy in Monster Land
Rygar
Cadash

Just to name a few....

Above mentioned shooters.

Also:

Air Gallet
DonPachi
DoDonPachi

My Favourite game on MAME is Aliens vs Predator, excellent side scrolling Beat 'em up

alien vs predator (1994 i think) and elevator action

Robotron
Discs of Tron

You really need dual joysticks for Robs and a spinner with up/down for Tron to really enjoy those though.

You should try some of theclassic beat'em ups from capcom:

Knights of the Round
Final Fight
Captain Commando
The King of Dragons

If you're interested in some truly geriatric-school arcade games, give Spy Hunter or Time Pilot a whirl. Incredibly archaic and yet ridiculously fun and addictive, imo.