What is the maximum level you can reach by the end of Planescape Torment, assuming you explore everywhere and do all the side quests?
I installed PS:T on the weekend and checked out various FAQs to find out how important each stat was (basically to see how little intelligence, wisdom and charisma I could get by on as a warrior) and to familiarize myself with the D&D rules. Since most references seemed to think wisdom is great, especially for the experience point bonus, I decided to check how much of a bonus it would actually give in terms of extra levels.
I thought I recalled someone mentioning level 25 as about the maximum level, but searching the FAQs and walkthroughs I saved (just in case I got stuck) the only instance of 'level 25' was someone saying they used an object very late in the game to jump 10 levels and become a level 25 fighter. I didn't want to read through any more of the walkthrough to see if they had played as a warrior from the start.
Anyway, I stuck the experience point requirements and wisdom bonus values in a spreadsheet and checked a couple scenarios for a warrior (a mage or thief should be similar).
Starting with a wisdom of 18 and putting a point into it at each of the next 7 level ups, you will have gained an extra level by character level 13 (ie without the bonus, you would still be at level 12), 2 extra levels by 17, 3 by 20, 4 by 24, etc (after that, for every 3 levels worth of experience earned, the wisdom bonus would give an extra level).
With a constant wisdom of 18 from the start, at level 16 you would have gained an extra level, 2 extra levels at 24, 3 by 32 and 4 by 39.
With a constant wisdom of 16 from the start (ie from what I have read, about the minimum to get the majority of relevant extra conversation options), you would not gain an extra level until reaching character level 31.
Wisdom may be required to get some dialog options, complete certain quests and to recover memories faster, but I don't think the experience bonus is that great unless you really boost wisdom.
