https://www.groundbranch.com/
The game is available on Steam
It still needs a lot more content and polishing. But a recent update to the AI changed it quite a lot.
Then be carefull, only the servers where the AI parameters have been worked up by the admins are really playable. The row ones are ridiculously hard.
For those who have already given it a try : the bots are now patrolling. They can react by overturning and surprise you charging behind your cover, so never feel safe for a too long time, or you may receive an perpetual deny

If you want to see that, I recommend the following server, that has very often several players in :
MilsimBreach Semi-Realistic
It is still a bit too easy for my taste, though still challenging. I use to have a nice experience each time I'm conected