Well it can be that chargers are crapping out on high current draw happening during gaming load, which is the highest possible. If power brick is crapping out at higest current draw it will drop voltage form say 19,5V( or whatver it provides) to something lower which might get detected as unplugged power brick by laptop. Almost all Asus laptops have power bricks from Delta Electronics which is China firm. I am not saying that they are crappy but nowadays everything is produced right up to the spec to cut costs. If the laptop demands max power of 300W it can draw 15,39 Amps of current from 19,5Volt power brick in ideal conditions. So you have a power brick which is probably rated at 15,5Amps which should be enough in ideal conditions of power grid, which they are far from. You can have power ripples or freq shifts which the power brick has to filter, but it requires more power to filter those out and when the power quality is crapping out power bricks can give out less Amps. Ideally power brics should have at least 1 Amp more than Apms reqired by laptop or they might crap out at high current draw when the grid fluctuates and you are gaming. You can buy surge protector of know firm and connect power bricks thru it and see if the unplugged power bricks return or buy higher Amps rated PSUs.
