Thanks for the feedback! True, it can be a bit long for a jam game. Originally it took me about two hours to beat, after some cost adjustments I can consistently beat it in about 30 minutes, which is still quite lengthy. The trick seems to be to rush level 3 drill and level 2 jetpack (level 1 is too slow to escape from deeper caves). After that you are equipped to get the reds and you can get yellows and green at a rapid pace also.
Working on the project post-jam is an interesting idea. I had some other things planned for the game that I had to cut due to time constraints. Would be nice to have an opportunity to bring them back.