Q*Bert Codes -

Gateway disks:
Look out for disks that do not spin like normal disks. These are gateways to bonus areas.

Swirly The Snake:
Red balls can only travel down and purple ones are Swirly Snakes. If Swirly The Snake comes out and chases you, jump onto a disk at the last moment and he will fall off.

Difficulty setting:
The difficulty only changes the amount of lives you have and not the enemies.