i have this happen in many games and other things. if something is full screen, sometimes windows 10 or something else will just seem to grab priority or something. ctrl alt del will bring up the blue screen but then i click for task manager it will open in the task view window you can see it but you cant switch it to front and if you do manage to its blank. nothing but a blank window. sometimes if i open another desktop the system will wake up again, and depending on what game it is i have been logged out or it crashes to desktop (skyrim CTD on those occasions more often that it recovers.)
so are you sure its the game (if on pc)? it might just be whatever it is windows is doing in secret when it seems to freeze everything. what confuses me is, it is definitely windows because you cant open anything else even task manager; nor can you alt tab to anything and have it come to the front, but its not using up the cpu or something - you can still open a second desktop for example almost instantly. its like windows 10 just freezes all programs running for no reason.