Currently I'm writing it like this: “I’ll have red.” “Okay, me too.” Blaztrmaztr420 hailed the virtual waiter, who was played by someone called niceguy100. Niceguy100 walked up to the table in his black and white uniform, and asked them what they wanted. Blaztrmaztr420 ordered them a whole chicken, garlic bread, spicy rice and red wine, and niceguy100 wrote their order down on a notepad. “Thanks snow angel,” blaztrmaztr420 said. “What the hell is a snow angel?” niceguy100 replied. The player names are 'blaztrmaztr420' and 'niceguy100', but at the beginning of a sentence, I'm capitalizing their names, even though that's not how their names are written in the game. How should I write this? Like this? : blaztrmaztr420 hailed the virtual waiter, who was played by someone called niceguy100. niceguy100 walked up to the table in his black and white uniform, and asked them what they wanted. blaztrmaztr420 ordered them a whole chicken, garlic bread, spicy rice and red wine, and niceguy100 wrote their order down on a notepad. Thanks for taking the time to read this.
Oh gosh, that's fine once or twice, but it hurts to read the longer I have to read it. It might be useful to have the characters call eachother by a nickname (Blaz, Nice, etc) and that way we can read the names more smoothly as well. Might kill two birds with one stone.
Nickname is a good idea, but if you have to, just use Blaztrmaztr420 and Niceguy100 when they come up.
Come up with an abbreviation for each name. Much easier to read it that way. When you read the names Blaztrmaztr420 and Niceguy100, especially the first one which is nearly impossible to pronounce, it takes away from the rest of the story as you try to focus on pronouncing it right.
It depends on the scene's point of view. If it's another player, then they probably won't be thinking of someone's full username in their own thoughts every time they think of that player. They will usually come up with a shorthand. Maybe instead of "racecars172" it'll be "racecars" or even just "race." Usually we can see this in the chat on those games -- people usually abbreviate when talking to each other.
Perhaps just give them easier names? It doesn't have to be realistic. In Ready Player One, the main character's names are Parzival and Art3mis. Obviously, unless these users were one of the first adopters of the tech, these names would be taken and a more realistic name would be Parzival763846343 and Art3mis12432534. I also agree with using their nicknames rather than handles. Games are fast paced and we need to be able to identify each other as fast as possible. Nobody would say "Blaztrmaztr420 shotgun behind you." By the time you finish saying their name, they'd be dead. It'd be "blaz, shotgun behind you." One or two syllables max. I play Halo online with friends almost every night, nobody uses full handles when talking.
Even in your head, you probably don't read/say "BlartBlaster1000" everytime you see you friend come online. Odds are, you'll abbreviate, like most people, to "Blart" or "Blaster" So, state the full handle once then stick to using a short-name that would make sense.
You also always have that edgelord, who think they're edgy with edgy names like Godkiller6-6 FukUrMa69 So edgy, LOL! Maybe they could be antagonist or something. As others said, you can pretty much abbreviate or nickname such as GK6 and FU69. Sorry, I'm not very good at this.