Mimimi's Magnum Opus.

Fantastic game, by the creators of Shadow Tactics: Blades of the Shogun (works in a similar vein to the (very) old Commandos game. You have 5 characters with unique abilities that you can control - though not all characters are available at the start, they become available after a certain number of missions. Most missions do not feature all characters at the same time. Currently I have completed 15 missions, the 16th is waiting - not sure if there are more. Though the game offers you some "challenge" missions (which I have not tried yet, but I believe they will involve replaying the old map with a different objective).
This is not normally a "stand up and fight" sort of game ... more a sneak around and do stealthy (unobserved) kills. It is not a FPS, rather an angled top view. There is a lot of saving and re-loading - that is the idea behind the game. Tactically, it is absolutely fantastic - you really have to be creative and use your brain to solve some of the situations you find yourself in. Having said that - there would be a large variety of methods for tackling a mission - making for lots of replay-ability.
I have played through on 'normal' difficulty, and it is definitely achievable (with some thought and effort). Looking forward to re-trying on 'Hard' level. Make sure you master the "showdown" mode, which is essential for completing more challenging situations.
Would highly recommend for those who like tactical games - have played more than 100 hours so far (on my first play-through), and absolutely loving it.

This is one of my absolute favourite games ever. I play exclusively on the steam deck. The gamepad controls are perfect. As are the graphics, vast maps, sound, story and music. I have nothing but praise.
The game mechanics are perfect too. Absolutly love the showdown mode, planning synchronised attacks.