FOF with airsoft is one way that works well. Just don't play a "game" but be serious about it.
I shoot as many "night" matches as I possibly can.
I train with LEOs as a volunteer "bad guy" in a variety of conditions.
I asked a friend, who was a DOC officer if I could interview inmates who had been convicted in shootings. They had to agree, but I learned quite a bit about what tactics may work, and some which probably would not, from talking to these guys. I asked them what they saw, what they were trying to do, etc. when they were shooting. The information about "why" they decided to shoot was also interesting.
Last, Play acting: This is an excerpt from the text I wrote and used for many years...
Scenarios and Situations. Yes, even without a FATS, this can be done. The author’s wife likes to give, and go to, murder mystery parties. Why not a Scenario party? Okay, don’t freak out! Remember, NO guns, we’ll use just an index finger and “air guitar” it. Have four of your shooting buddies draw up 4 scenarios. Then when they come over to watch the game, do one each commercial break. Rotate through as play actors, CCW holders, and moderators. Read your scenario and set-up the situation, and then let them act it out. Set some basic ground rules for the play actors and CCW holder and try it out. Verbal commands are necessary, as is feedback. This is to be taken seriously. If someone is goofing off, just quit and don’t invite them to participate next time. You can use cover, movement, element of surprise, etc. as great training aids. Do not berate each other, try to improve each other.
One thing I have learned, there are very few "textbook" lethal force encounters. Planning and practicing reactions and methods is certainly important.