A few notes and tips:
- Your character is, for most intents and purposes, undead and immortal. That means death is really more of a minor setback than anything, barring extreme circumstances like pissing off gods or being completely burned to ashes. This also allows you to restore health through rather macabre means like drinking blood/embalming fluid or stitching yourself up with a needle and thread, as well as slowly regenerate health over time (even with less than 20 CON, though it will regenerate faster when that number goes up).
- Your strange nature also allows you to do some pretty bizarre body manipulation at times; swapping out eyeballs and limbs and so forth. This is useful to recover some memories and earn experience.
- As in Baldur's Gate (and most D&D games), combat with most foes earns you a pittance for experience; you earn far more for completing quests and solving puzzles. Having a high Intelligence and Wisdom not only helps with many quests, but earns you bonus experience, so put most of your points into them to start out and try to push Wisdom up to 25 over the course of the game.
- Contrary to second edition rules, your character cannot multiclass or dual-class. Instead, you can switch between one of three classes (Fighter, Thief or Mage) by talking to certain NPCs. All three classes level up independently of one another, though you keep any HP you've gained. Your HP also raises in accordance with your highest class, so try to keep Fighter ahead of the other two.
- Don't forget that your HP rolls are randomly determined when you click "Level Up" as well. Save before you click it, then if you get a bad roll, reload and try again. You don't need 9 or 10 each time as combat is a fairly minimal part of the game, but try to aim for the higher end of the scale.
- Talk to every named NPC. A lot. They all have a ton of dialog, and it's absolutely saturated with atmosphere. This is easily the game's strongest aspect and the meat of the whole experience. (Many have quests to complete as well.)
- By the same token (and unlike BG), you're also not locked into a particular alignment; lying and doing silly things will make your more Chaotic, keeping promises makes you more Lawful, doing good deeds makes you more Good, and being a jerk makes you more Evil. You start as True Neutral, but do enough things in any direction and you'll shift alignment.
- There are also several factions for the player to encounter; some can be joined while others can't. Joining one faction may earn you enemies in another or shift your alignment in a way you don't want (for example, joining the Chaosmen will make it extremely difficult, if not impossible, to become Neutral or Lawful again) so consider carefully before you commit!