No purchase is required to play any or all of these games all weekend long. All you need is a Steam account (available free of charge).

The 10 titles being offered are:

1. Awesomenauts
2. Blade Symphony
3. Company of Heroes 2
4. Don't Starve
5. Grid 2
6. Injustice
7. Killing Floor
8. Payday 2
9. Trine 2
10. XCOM: Enemy Unknown