I don't think Civ5 is very replayable. Mods don't help much, in fact both Vox Populi and NQMod made the game even more repetitive for me (the "balancing" they do is in fact done the bulldozer way - make all the civs and policies flat). After 128 hours of playing I think I can tell why the game is so repetitive. 1. Tall race for World Wonders is way OP The only things players race for are good city locations, World Wonders and, later on, City State allies, sometimes it is also important to convert citizens to your Religion, but it's negligible. Penalties for having many cities are so severe that they penalise any form of further expansion. Once you discover how OP the World Wonders are and that you can grind even more Culture when you go for Aesthetics to unlock policies even faster (my last Siam game on Emperor: in the mid-game I was 6 Social Policies ahead of the remaining civs because of the boni from Aesthetics branch) you realise no matter what, you need to funnel Production towards World Wonders. 2. Civs barely differ (and that's why Venice is so much fun) Shared technology tree, social policies, buildings, units, beliefs... B-O-R-I-N-G. The only fun civ to play is Venice as it is really different in playstyle, but can be easily mastered. 3. Snowballing The only way to stop you is to wage war against you to enforce training military units, and even this may fail if you're wealthy enough. Otherwise you'll grind that Culture or Science continuously, because the same resource is spent on making collecting it faster. Exponential growth is a serious problem. 4. Boring City States Except taking up good map spots and providing World Congress votes they are absolutely useless. A great example of unnecessary complexity in game design. The worst thing is I haven't heard nor read that any of these have changed in Civ6 and I have no intention of purchasing a game with exactly the same flaws. Either I find out there's a mod I've been missing on for almost a year or I'll switch to a different title. And what do you think?