Terraria might be good.
System requirements from Steam:
OS: Windows Xp, Vista, 7
Processor: 1.6 Ghz
Memory: 512MB
Hard Disk Space: 200MB
Video Card: 128mb Video Memory, capable of Shader Model 1.1
DirectX®: 9.0c or Greater
--
https://www.youtube.com/watch?v=wsbvaQcuW9k