Would it be possible to use a cloud server instead of dedicated server for running high speed Action MMO?
I believe so, though I don't think it's much different, a cloud service such as azure or amazon EC basically gives you a stack of VM's to deploy, its also pretty pricey. IIRC Azure for 10k dual core instances would be like 2.5ish mil a month.
I was thinking about a monthly rental with midphase, or cheapname. I can get cheapname a month for $20.00. But it's only for limited resources. But for my project it might be just enough.
You can also use something like NodeJS and web-sockets if your multiplayer needs are not too big. There is a demo on the Godot repository with some examples. It may be cheaper to host, depending on the pricing (I haven’t really looked into it myself).