if you only had 5 games you could keep and 2 controllers. The rest is gone FOREVER.

[Mordan]

you can keep a MD of course.

mine would be

-Adventure of Batman and Robin for the 2 players, graphics and music.
-Psycho Pinball : potentially replayable for 100 000 hours. 4 well designed tables.
-Eternal Champion for the 2 players.
-Thunder Force 3 : the shooter which I like best.
-X-Men Clone Wars: for the music variety.

[retrospiel]

Streets of Rage 2
Castle of Illusion
Revenge of Shinobi
Thunder Force IV
Sonic 2

EDIT: but I'd be missing the Shining Force games, Monsterworld III & IV, the other Bare Knuckle games, Golden Axe 1/2/3, Quackshot and World of Illusion, etc.pp.

[Thunderblaze16]

lightening force
dynamite headdy
gunstar heroes
alien soldier
rocket knight adventure

[Armoured Priest]

Oh man, that's rough...but I think I'll go with:

Shining Force 2 (needs no explination as to why; between the number of characters, the story, and the tactical combat)

Sword of Vermillion (I personally get a kick out of this game. I periodically play through it even today).

Gaiares (Arguably one of the best shooters on the Genny, and one of the few that I never got around to finishing, so I'd like to spend some time with this one).

Arcus Odyssey (Co-op Action/RPG isometric. This game is a good time with a friend. It is a bit quirky, but is underrated).

Star Control (Good for both the stratagy element, as well as the competetive two player aspect).

[Crackdown]

Streets Of Rage 2
Pit-Fighter
Sensible Soccer
Dragon's Fury
Outrun

[makinagenesis]

mine -

Sonic 2
Monster World 4
Phantasy Star 4
Bomberman
Shining Force 2

[Sega Genesis]

Rastan Saga 2
X-Perts
Deadly Moves
Fighting Masters
Race Drivin

[Assault9]

Championship Bowling
Side Pocket
Superman
Warsong
Vapor Trail

[profholt82]

Revenge of Shinobi
Road Rash II
NHL 96
Thunderforce III
Tecmo Super Bowl

[ShadowHawk]

Phantasy Star 2
Phantasy Star 4
Phantasy Star 3 (never beat it wat the hell)
Sorcerers Kingdom

[Kamahl]

Rastan Saga 2
X-Perts
Deadly Moves
Fighting Masters
Race Drivin

Loool, that would be a good way to prevent yourself from gaming ever again.

Mine would be:
Streets of Rage 2 (obvious)
Thunderforce 4 (needs a shooter)
Gunstar Heroes (2 player awesomeness)
Shinobi 3 (if I ever got bored of it I'd just use it as a music player)
Ecco 2 (because i've never beaten it and a punishing game is needed)

Alternatively:
Alien Soldier (just freaking badass, doesn't get old)
Beyond Oasis (combat makes it more fun the ecco 2, fire sword never gets old)
Ranger-X (I just really like the game)
Langrisser 2 (to use my head)
Contra Hard Corps (multiplayer + tons of replayability)

Or maybe from the Sega CD:
Robo Aleste (needs a shooter)
Android Assault (needs more shooters)
Silpheed (another shooter doesn't hurt)
Soulstar (to prove the sega cd hardware isn't useless)
Popful Mail (because it's just plain fun, replayability due to different characters)

There's no sonic because it gets insanely easy after you get super sonic, and it would be a wasted slot over time.
Shining force isn't in the list because if it's for the rest of my life I'd rather just play battle after battle

Making a 5 genesis games list is incredibly difficult. Too much greatness to choose from.

[Splatterhouse5]

01. Streets of Rage 2
02. Toejam and Earl
03. NHLPA 93
04. Herzog Zwei
05. Mega Bomberman

[Kamahl]

Um... Toejam and Earl is a pretty good idea for something like this. Multiplayer + Randomly generated levels? Yeah, probably the best game for this type of thing.
Shame I don't like it

[Ghost Soldier]

1. Toejam and Earl
2. Sonic The Hedgehog
3. Streets of Rage 2
4. Micro Machines
5. R.B.I. Baseball

[ShadowHawk]

lol at the Hard Driving

only game as a kid that brought me and my buddy more laughter and fun by smashing it with a hammer in the middle of the street. And this was in the mid 90s

Only game I ever destroyed