atari2600land has updated his maze/collecting item games GoSub, which has seen it’s initial release for Virtual Boy a while ago. Collect treasures with your underground boat in a maze!

There is also GoSub and GoSub 2 for the Atari 2600.

Release notes:

I have to change some levels because of the sub’s new size. I’ve done this up to level 9. I’ve added a level select screen. Press select at the title screen to get to it, and left and right to choose a level and start to start