Re: XCOM Enemy Within
Early on, enemy health displays don't matter very much. All of the aliens die in two (or fewer) hits, regardless of what you hit them with. The only time it causes problems is if you lose track of which aliens you wounded and which are still at full health, which only really happens if you lose sight of the enemy.
Later on it can get really stressful though. It's hard to gauge how close a Muton is to dying, so it's never clear whether you should focus one down or run for cover. It's also impossible to tell when a guaranteed grenade hit would be just enough to finish something off. And every new enemy type you encounter feels all the more mysterious and scary when you have no sense of how hard it will be to kill.
I like the "learning through experimentation" gameplay that this encourages though, and I like the added drama that the imprecision adds to the game.