1. Street of Rage 2 - Has some of the best music on the genesis. It's fun to beat the shit out of people with a friend.
3. General Chaos - great fun to be had scorching people.
4. Gunstar Heroes - Great coop fun, cool style, fun weapons.
Seriously Streets of Rage 2 Stage 3 Part 2: Alien Power is one of my favorite songs EVER!!!
um..... wow I'm lameGeneral Chaos is probably the only Sega game I rented even when I had the Sega Channel!!!!
and Gunstar Heroes is a game that I still play at least yearly to date.
I got such a purist hair up my ass last year that I bought Genesis after Genesis off eBay 'til I got a working system just so I could play (excluding the previously mentioned titles):
1.Eternal Champions - another great Sega soundtrack, and phenomenal fighting game as long as you NEVER heard of the "Sega Activator"
2.X-men / X-men 2: Clone Wars
3.B.O.B. - Sidescrolling at it's best
4.I know Ross mentioned Shining Force, but dammit, he's dead to me... so Shining Force 1 and 2
5.Zero Wing (cliche and the godfather of memes, but you got to know your roots, for great justice!)
p.s. At first I was surprised to see almost all my favorite games mentioned in only 6 posts... then I remembered we were talking about the Genesis here.