m50 is not ideal for gaming due to small soundstage though sound quality is not bad if you get them closer to $100. the m50 is so much nicer than the m30 [i gifted the m30 a few years back and own the m50].
for gaming though i'd definitely look at basroils suggestions. i will mention that the 558 shares the same drivers as the 518 [and 598] so you can get the same sound quality for cheaper. what you pay for is build quality though [which is greater on the 558 and 598]. the ad500x [and 700x, or a500x/a700x closed cans] are going to have a bass light sound which makes them more advantageous [hearing footsteps] at the expense of being less impactful and exciting. the 558 [518 and 598 too] will be about average and more neutral and are fairly easy listening.
if you wanted a complete headset.. the game one [neutral, based on the hd598] the game zero [bass light, more like ad500] are good if you get them on deep discount though you may need to stretch the budget. for cheaper than $100 the hyper x cloud isnt a bad choice [its based on the takstar pro 80 headphones] though i think some of the hifi headphone choices above are going to be a bit better.