ToME: the Tales of Maj'Eyal

I was hoping maybe some of the better players out there could write a quick non-class specific summary of common mistakes, tricks, strategies, etc., like places/enemies to avoid, charms to look out for, when to tunnel, quick tunneling overview for those unfamiliar with the concept, tips for early survival and basically all the tings you could get away with on nightmare, but would spell your doom on insane.

PS. Shite, I just found bpat's insane guide, face-palm. I knew such a thing existed, I don't know why I was unable to find it earlier, had to google search it.

bpat's insane guide is a bit outdated, but is still mostly accurate. Archer is a really good class instead of an awful one and Cornac is now one of the best races[Better then Thalore, IMO]. Doomelf and Drem are also very good races, but they're DLC only and somewhat difficult to unlock.

Cathbald also has a few insane guidey things.

My own personal advice for Insane is to play very cautiously in the T2s. Being cautious is good in general, but the T2s are probably the single hardest part of Insane. Playing cautiously means scouting diligently, inspecting rare+ enemies to see if they have dangerous talents, digging to make good terrain and being ready to run back to the previous level at the drop of a hat.

Oh, and never bother with the Dark Crypt on Insane. No matter how overpowered you feel, you'll probably still die horribly.