I haven't played with my psp for about an year, but when I do play it I love Lumines. You have to match the coloured blocks together. Sounds silly but it's addictive!
Ape academy is also quite good, lots of mini games.
I love Lumines too...I on my third replacement original PSP model as they seem to wear really easily and I hardly use it .... my last one is starting to go towards the PSP light in the sky too
What kind of game is Tekken? What does "GTA" stands for? Sorry I'm really ignorant...WOW! TBH I haven't played on mine for about a year! Boyf and me both bought one, but I lost the chargers (yes both of them!) so it's been put in the cupboard for a rest. I tend to use my DS more.
What about Tekken on the PSP? Not had a chance to play it yet myself, but it's one of my favourite games on the playstation consoles.
Can't think of any other games apart from GTA, depends if you like that type of game tho! I'm too lazy for that type of game tho!
Luxor and Twisted Metal, which surprisingly is really fun. I have Sims 2, but it got on my nerves b/c every single second she either was hungry or had to go to the bathroom. I couldnt do anything else but feed her and take her to the potty. I got sick of it and havent played it since.