The amount of mechanics that the game simply doesn't tell you about is super frustrating.

For example, did you know that all myth units gain 20% increased hp and damage when you age up? I didn't until I noticed it by accident during a game yesterday. This is an absolutely enormous increase in value for myth units unlocked in the earlier ages, and unless I'm just missing it, the game is perfectly fine to never mention it at all. It also doesn't mention that idle fishing ships are not considered idle villagers, so I hope you know to look for the "idle fishing ship" banner that I bet you didn't even know existed. Also, did you know that having a villager construct a farm will have said villager automatically deposit any resources they're carrying once the farm is completed? Very useful when shifting large numbers of villagers from wood or gold to farms.

Share some more of your "I really wish the game told me about this!" tips below.