I like TAC. The most popular alternative, from what I've read, is Religion and Revolution, a more complex game based on TAC.
raystuttgart sums up the difference well. "For a beginner, try TAC --(very stable, focused on improvements, adding only a few new concepts, very well explained). For a more experienced player, try Religion and Revolution -- (also very stable, based on last TAC release but much bigger, adding many new concepts, well explained)"
I think TAC has quite a few changes. Guns are expensive. When you're weak natives attack more quickly, particularly your neighbouring tribe, which will always attack. Cuirassiers, the most powerful land unit, are new. You can add Elder Statesmen without the King increasing his army. Silver, rum and cigars are all useful in the end game. Cloth is necessary to build wagon trains and ships. I could go on.
I've won the vanilla game on all maps and difficulties, yet my first four tries at TAC on Explorer led to quick wars and defeats. I had to step back to Pioneer in order to win. Now that I understand the full game better I can start climbing up the ladder again. I think it could take a while, which is good.
