1. More difficult requirements for upgrades (more of each type, or combinations required) 2. Stims requiring more plants (1 green for a medical is way to easy, even if you have limited stim space. Perhaps change it to 2 green + 1 blue/white...wtvr) 3. Archery challenges or a range with a score system for dedicated bow practice 4. Repeatable hunting challenges that require using the bow/blade and collecting a certain number of hides in a certain time limit.
"All your sweetrolls are belong to me." Video play throughs at - http://www.youtube.com/user/DreadArkive