Go to https://macheist.com/ and play the game. Basically just keep walking and you should get the games 
Also make sure you raise the donation to $50. you don't have to actually pay but that way you can progress and get the games.
Here's a gameplay of the 3 free games you'll be getting:
Tip: use scroll to make him move faster
Source : http://www.epicbundl...es-extravaganza
If you're struggling:
Spoiler
I'll post a new giveaway when i find one
