[mauve]

X-Com is a decent example of this. The only major upgrades the enemy ever gets are Chrysalids, Heavy Plasmas, and Psychic ability, and the former two come relatively early and the last one around mid-game. Meanwhile you're constantly beefing yourself up throughout the course of the game, with the only major stumbling blocks being either surprise psychic mutiny or fantastically hilarious group wipes. By the end of it you have a nigh-indestructible army of soldiers who can snap-shot at 100% accuracy across the length of the entire map while your tanks run around scouting for them and eating alpha strikes.

Nighttime is still terrifying, at least.

A lot of other strategy RPGs are similar, depending on how you play them. Both FFT and Tactics Ogre can be outright trivialized by certain powers, for example.

I tend to feel that it works better for games where it's logical and consistent with the game's premise for it to do so. Not necessarily in a "I'm killing stuff so I get more powerful hurr" sort of way. X-Com, there, for example, is more about catching up to the aliens and getting on an equal footing with them than it is about the ever-increasing numbers. Megaman, as not fond as I am about the design, is at least (mostly) consistent in premise as to its gameplay.