Good PC Games

So i wanted to play Watch Dogs but since my pc couldnt handle it, can you just reccomend some good pc games that can run smoothly on my pc? Specs:

Processor Intel(R) Core(TM)2 Duo CPU T5870 @ 2.00GHz

Manufacturer Intel

Speed 2.0 GHz

Number of Cores 2

Video Card ATI Mobility Radeon HD 4300 Series

Manufacturer ATI

Chipset ATI Mobility Radeon HD 4300 Series

Dedicated Memory 512 MB

Total Memory 2.2 GB

Memory 4.1 GB

Operating System Microsoft Windows 7 Ultimate Edition Service Pack 1 (build 7601), 64-bit

Service Pack 1

Size 64 Bit

Edition Ultimate

Display Maximum Resolution 1366 x 768

DVD hp CDDVDW TS-L633M ATA Device

CD hp CDDVDW TS-L633M ATA Device

Drive 1

Size 368.1 GB

Free 41.2 GB

Drive 2

Size 97.6 GB

Free 14.6 GB

This is a vague question since there are so many games available. Given your hard drive space and specs, older and/or indie games would be more appropriate, but what genres do you favor, is online important and is there an age limit?

@Postosuchus: I have a passion for open world (but pls not gta or fallout) and no age limit and i am open to other genres although if you dont know a good open worldgame, i love platformers.