With the permadeath thing, you should put some thought into anti-save-scumming methods. The best method isn't to restrict the player from save-scumming, but to make it pointless.
Here's a plan I thought up.
- use your own randomization code
^ this allows you to control the randomness better
- each unit gets their own random seed
^ this ensures the order in which units move doesn't change the outcome
- each turn, roll one throwaway random number for each unit
^ this ensures you can't exploit the predictableness of the shots the next turn. Each turn has fresh percentages.
Basically this would eliminate the simplest "take shot, reload, repeat" type exploit which means 100% of your shots hit home.
A remaining exploit would be if you got a perfect shot with one character, so you rolled back and used that shot on a different enemy. Unfortunately, there aren't many ways to fix that possible exploit without creating more other exploits. e.g. say you said that each units hit chance changed per step you took, or on where you were standing, or was different for different enemies, but still deterministic, then players would start reloading to try out different combos until they hit the "magic one" for that round. Which would be back to the original problem that save-scumming is tempting, because you can max-out your longterm gain, but it kills the fun.
So, the above plan for determinism is the one that reduces the amount of save-scumming that would ever be attractive in terms of maximizing your hit/miss ratio.
Some other steps can further reduce the incentives to save-scum:
- make it so that taking a shot, even if it misses, gains XP with the weapon faster than an actual hit. near misses would be worth the most. Basically someone who gets perfect shots won't gain weapon skill as fast as those who make mistakes.
- experiencing death of an ally, or taking hits/near misses, should have short-term morale effects, but make it so long-term they become hardened by the experiences, and gain bonuses in other situations, e.g. they're more calm in combat situations so they get some amount shot bonuses etc. Players who save scum away all allied deaths or danger, will end up with wimps.
Basically these things would create incentives to just play through the game and almost never to save-scum.