I also recommend Timesplitters 2. I've gotten very few GCN games (mainly because i Prefer pc games). Probably 10 total. Timesplitters 2 was probably my favorite. I spent the most time playing it and actually beat it too.
Most games I never finish cause they bore me ~_~.
And KoH (its his bnet kickname), don't mind d3v. He's practically whoring himself out to sony.