First up you are missing the religion victory, spread your religion and purge the unfaithfull (using the inquisitors) and burning down other religion holy cities. Don't forget to have the "other religions won't spread to your territory" for this one, and try to force your "freinds" on the same continent as you to adopt this civic too.
For a tower victory you need I two mana types of each category (alteration, necromantic, divine, enchantment) so you don't need ALL of them... second more there is (or used to be) a project that produces even more mana nodes... this might be what you need to look into especially since you cant change mana types on nodes you have already build on.
That's a bit of a theoretical answer I think. The religious victory conditions, as they stand, are very difficult to meet, even with judicious use of the Inquisitor unit. I'm far more likely to win in another way before ever hitting the religious mark. I think there needs to be a more balanced way of managing the Armageddon Counter in general. Unless you run an Evil Civ or Elohim specifically, you are pretty much railroaded. I think that fix is coming up in version 0.30.
I keep reading that only two mana types are needed to build the corresponding towers, but for whatever reason, the BtS version seems to require the full suite of three or four. I did manage to win once with the Tower of Mastery, but that's because I was lucky enough to have a good supply of nearby mana early in the game (large map -- big & small islands, and I did use the Rite of Oghma just for that last missing mana). That's uncommon though. On the other hand, as I was surprised to see how eager some Civs are to trade precious mana for some cheap resource commodity! That did help...
The Altar can be pretty easy to build in some cases. It did happen in a couple of games that I had a plentiful supply of Great Prophets -- completing the Altar circa 400 turns in both cases. This usually does not work out that way however. In most cases, I just don't have enough great people to finish the Altar (I sure like their bonuses though!)
By the time I get to the end game, I'm usually close to several winning conditions (Altar, Tower, Domination, or just points). That's actually a good thing! This means that, although winning conditions are by no means easy to achieve, they seem relatively balanced. I do not win every time, far from that, and I don't think that's an issue because otherwise the game would be too easy. So, for those of you grappling with a chance to win, play the game more than once obviously. Give yourself a better chance to learn the long-term strategies of the game in the first place. You will get shoe-horned into unwinnable positions often enough -- if so, toss the game, try again.
Hint: avoid starting positions in jungle or fully forested areas, unless you run the elvish Civ. Hope this helps...
