Given that so many people in this thread mentioned Eschalon, I decided to play all three games in the series. They are quite fun. Most importantly...
Very low system requirements
Finishable
Book II is probably the best. Book III is probably the worst.
Many of the complaints about Eschalon in this thread seem inaccurate to me. If you have any questions about a specific complaint, send me a message. Each Eschalon game has only one major shortcoming:
Book I: Your character's ToHit stat is out of balance compared to the enemies. They seldom miss; you will often run away to rest, then return to fight some more until you finally kill the enemy.
Book II: In Book I, the world map in the .pdf file was useful (also available as an item in the game). In Book II, the designers inexplicably produced a lower-quality world map, which I found basically useless.
Book III: Books I and II are very well organized, showing a sensitivity to the needs of players. Book III...for some inexplicable reason, the designers tried hard to make the game obscure.
Too many dependencies in quests--to finish quest F, you first need to finish quests A, B, C, D, and E. If you get stuck...and you will...because an area of the world map is not readily accessible...or because quests A, B, C, D, and E don't seem relevant to each other or to quest F, you'll be forced to consult a walkthrough.
Too many obscure puzzles.
Too many tasks that aren't logged in the quest book.
Too many unexplained aspects of the game (for example, the numbered tokens).