Issues:

• The campaign selection button is highlighted before you even press it
• The default campaign's levels don't automatically show up
• Exiting a level with backspace puts you back in it again. Next backspace pulls you out
• I've not played with task switching
• I think somethings not quite right about lives count
• Weird box characters in the display

I forgot to mention, "r" restarts a level and "n" skips the level and lets you move onto the next.