I guess I'll be the sole voice to go against the flow in this thread
My opinion on the GC...
GC is like N64 in that there are only a few good games worth mentioning.
IMO, SSB:M is very childish. It's a VERY dumbed down fighter.. simple to beat and gets old after 20 minutes or so. If I had to pick between DOA Volleyball and SSB:M, I'd rather play nothing.
The GC titles I own:
Metroid Prime (perfect)
Zelda WW (childish, too easy)
Zelda OOT & OOT Master Quest (remakes, nothing special here)
Zelda 4 Pack (Zelda, Zelda II, OOT, and majora's Mask) (remakes, nothing special here)
Sonic Mega Collection (for my girlfriend)
Super Monkeyball 2 (childish)
Resident Evil remake (kick ass)
Other than that... there isn't much worth mentioning other than Eternal Darkness, Viewtiful Joe, and the MGS remake.
To me, GC has VERY FEW "must own" titles as opposed to PS2 where I could ramble off a laundry list of must own titles. The main reason for that... the majority of GC titles are, to me, very childish. Take away the titles that can also be found on PS2, the titles in my list, and the sports titles... and you aren't left with much.
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That's not to say it isn't a good system, because it is, and it definitely has potential... it's just that the current selection of games aren't very flattering.