I saw this posted on another website and hadn't seen anything here and I thought this group would appreciate it:
https://bearingsonly.net/
It's made by a submariner to get your reps and sets in - interpreting sonar data to take out an enemy submarine while also not getting killed. Be prepared to die a lot.
All the information you need is on the website, including background info on the creator of this great little program.
Enjoy!