Make a feature broken or useless in one change.

Let's play a game: you somehow have ended in the dev team, and have decided to troll by making something either completely broken or totally useless, with one change. It can be a unit, a civ, a map, anything as long as it's imaginative.

Just avoid changes that are just ridiculous number tweaks, like "+10 000 to cavalry archers attacks", these are too obvious and unimaginative, anything can become broken or useless if you just tweak the number hard enough.

​

So I will start with this one:

Sicilians:

First crusade: removed the 5 Town Centers limit. Additionally, if the player has at least 10 Town Centers, the Sicilian theme will be played for every players in the game when this technology's research is completed.