1047 Games has seen Splitgate blow away all of their expectations, so much so they had to take the game offline (it's back now) and extend the Beta.
What's been called Halo with Portals (that's pretty accurate) has seen it smash through the total number of player repeatedly, which is due to it being free and cross-platform between PC and Consoles. They mentioned at one point recently they saw over 100,000 players which is absolutely insane considering there was only 4 people working on it up until recently.
They've announced that they've hired more staff to help cope with the demand. Not only that, they've raised $10M USD in funding to continue expanding the game. Due to all the server issues though, the Beta has been extended for a while although they're not saying how long.
While still in Beta a big update did drop which includes multiple new maps, a new game mode, anti-cheat improvements, various crash fixes, upgrades to the custom game browser and more fixes.
Right now they've closed off the main game playlists like Casual and Ranked while they again boost up their servers. For now, you can only play Custom games - which is actually a pretty great feature allowing you to host and tweak plenty of rules. Although at time of writing, even Custom games seem to be having issues.