To try out the game, go to Super Mario Bros. 3/Web Build/Web Build.html
If you downloaded the Unity Web Player but it's bugged and says that you still need to download it:
- If you're using Google Chrome, try a different browser first
- go to Super Mario Bros. 3/Assets/Scene_0.unity
- click on the Play Button at the top-center
Use arrow keys to move X to jump, Z to do action
Use the two blocks right above you at the start to get upgrades (for testing purposes)
- Hit one block, get mushroom
- Hit the other, get tanooki
Run to the right, away from the big Luigi