For doom, go for any type of djent band. It was a style popular in the early 10's. Big bands are Periphery, TesseracT, Architects, and Vildhjarta. And of course, I would be remiss without mentioning Meshuggah, they're probably closest to what you're wanting. Meshuggah aren't djent themselves, but they're the creative ancestor of it. Basically every djent band is trying to be melodic Meshuggah with whiny vocals, but that's just me. Also worth noting, I'm pretty sure Mick Gordon specifically sited Meshuggah as an inspiration.
https://youtube.com/watch?v=4A_tSyJBsRQ
MGR is a bit harder, I'm less familiar with more melodic styles. That weird electronic power metal type thing that game has going on is kind of unique to it. If it isn't, I'm not informed on what they're aping. My best recommendation would be to dig into power metal and see what you like, but bear in mind most power metal has a much bigger fantasy bent and isn't going to have that technological sound the MGR OST does.