So as I’m sitting here looking at vision-based traits for a character with magical eyes, it dawns on me: why buy Blindness? Blindness is a whole -50 points. Seems like a worthwhile amount for such a limiting disadvantage. Consider, however, the following list:
- Bad Sight (Nearsighted) [-25]
- Colourblindness [-10]
- Night Blindness [-10]
- No Depth Perception [-15]
- Tunnel Vision [-30]
None of those are mutually exclusive, and they add up to a massive -90 points. Obviously, something is wrong here. Now any reasonable GM would just forbid that combination outright — but I don’t want to be reasonable, I want a concrete reason to give to my players for why the rules don’t work that way. Finding that reason is deceptively simple, but you have to think a little outside the box.
Blindness is -50 points. This suggests that not being blind is a 50-point advantage that every character has by default; effectively Vision . Now, if Vision is an advantage, does that mean the various disadvantages are limitations?
- Vision (Nearsighted, -50%) 
- Vision (Colourblind, -20%) 
- Vision (Night Blind, -20%) 
- Vision (No Depth Perception, -30%) 
- Vision (Tunnel Vision, -60%) 
All of those work out to the same effective cost as their actual-disadvantage counterparts. But taking them together, you can’t take more than -80% in limitations! -80% of 50 points is a -40 point discount — and so, it would be quite fair to tell your players that they can’t get a discount of more than 40 points from Vision disadvantages unless they’re actually blind.
“But wait, Mr. GM!” they cry! “I have Hyperspectral Vision , doesn’t that mean my Vision advantage is more expensive!?”
Sure, I say! Vision (Hyperspectral, +50%; Nearsighted, -50%; No Depth Perception, -30%; Tunnel Vision, -60%) . You’ve got some serious colour perception but lousy everything else — are you playing a mantis shrimp?
While no GM should be afraid to stamp out munchkinism where they see it, I hope this gives you a couple rounds of ammunition to back you up — and perhaps makes you look at disadvantages with a new eye.