The listing, HackyZack - Steam Key has ended.
Steam key for HackyZack
https://store.steampowered.com/app/508530/HackyZack/
Precision-platforming puzzle-stunt game.
How to activate Steam Game Key / Code
1) Launch Steam and log into your account.
2) Go to Games then click on Activate a Product on Steam.
3) Enter the code you purchased.
4) Go to your games list in Steam, highlight the game, and click install!