Reddit reviews BeyerDynamic DT 990 Premium Headphones 32 OHM (483958) with Slappa HardBody Headphone Case, FiiO A1 Portable Headphone Amplifier (Silver) & 32GB MicroSD High-Speed Memory Card

For gaming you'll definitely want something open with a good sound stage, and the M50x most certainly doesn't meet that criteria. While they are a fun headphone to listen to and quite comfortable with upgraded pads (Shure 1540 or Brainwavz HM5 pads to name a few) - they just can't compare to an open headphone for gaming.

If you're looking at something in the $150 price range that'll work for both of your requirements, I suggest you take a look at the Beyerdynamic DT 990 Pro or Premium. Great sound stage, great sound overall and a slight bass emphasis, which is pretty sweet for an open headphone.

Do keep in mind that the "Pro" version is 250 ohm, and will need some amplification to perform to its full potential. The Premium version comes in 32 ohm, and won't need to be amplified.

EDIT: Here's the 990 Pro (250 ohm) from Focus Camera via Newegg for a mere $125. That's a pretty sweet deal for this set. https://www.newegg.com/Product/Product.aspx?Item=9SIA29P3MC6389&cm_re=dt_990-_-9SIA29P3MC6389-_-Product

Aaand here's the 32 ohm Premium version with a hard case, a micro SD card and a small Fiio amp for $189. This is honestly an even better deal, imo. https://smile.amazon.com/BeyerDynamic-Headphones-Headphone-Amplifier-High-Speed/dp/B01JOQ2UMG