Every tile on every map I start with is covered in water. I know the tiles are not water because the UI says so when I highlight them. Also, all the counters and trees are poking up over the service. But everything is water! I can't find anything online about this.

If you don't get any help here you can always ask support if the game isn't working as intended

It seems like a problem with your GPU. Your PC configuration either doesn't meet the requirements of the game, or your GPU drivers are not up to date or you have two GPUs and the game is currently running on the integrated GPU.
Try to locate file aggressors.log and copy over the content here. I will try to help.

Thanks for the replies, folks. A reinstall did the trick for some reason. It also runs fine on my potato laptop for some reason. Probably just a GPU thing.

Good to hear that it is working now and thank you for the update. It was almost for sure some kind of GPU issue. If you experience anything similar, please try to update GPU drivers and if you have two GPUs on your laptop, set up the more powerful one to be executed with Aggressors (in Nvidia Control Center or ATI Catalyst).
Enjoy the game.