Gothic 1 & 2
Gave me more sense of progress than any other rpg I've played. A lot of rpg's rely pretty much on "numbers" and killing more things to increase more numbers to kill more things that get progressively tougher as you go along - nothing is too strong for you because these games are made so that enemies are more or less in your tier of strength and are easily defeated.
In the gothic franchise, however, you start out as a piece of crap, and no npc gives two shits about you. There are serious restrictions in what you can fight, because almost everything is tougher than you, so you can't just plow through everything you see like in some hack and slash game, you have to pick your fights carefully.
The great thing about it is that a lot of the enemies you'll be fighting in latter chapters can also be found at the beginning, and this is how the game sets it's barriers and restrictions in it's open sandbox world, a lot better than separate stages or silly invisible walls. Come face to face with an orc at level 1~5 and it will quickly brush you off in one blow. This is a good thing, because then it's all the more satisfying when you get really strong (the end-game kind of strong) and start plowing through hordes of orcs without breaking a sweat.
I could go on about how the story and character interaction fits perfectly into this you're-weak-at-first-but-you-kick-ass-later mechanic, and how getting into disputes with rival npc's actually gets you emotionally involved withouth so much as a cheesy "they killed my wife and kids and dog and turtle, and now I'm aaannngry garrr!!111" cliche, but ... oh, I already did. Never mind then.
Anyway, this game definitely deserves to be high in the top 100.