Nice, by the looks of it this game seems to be heavily based on the Salmon Run mode of the main games. Its a mode where players need to survive 3 waves of salmons in an arena and collect eggs by defeating bosses, its PVE and has a tight game design where enemies have a clear AI behavior and specific weaknesses to be defeated while also using a lot of parkour platforming.
From what I can see we will be facing the same enemies now in some sort of open world, and instead of a group of players we will have more weapon customization and a lot of abilities. It has the potential to be a fun 3rd person shooter with platforming to explore the world, I'm sold already lol.
Btw, for people who are new to Splatoon, the games have singleplayer campaigns that can last from 5 to 10 hours depending on how much you want to do and unlock, the levels in these games are a lot linear but still very well made.
Wario64 posted on twitter that Raiders digital version is $50, it seems Nintendo is really doing that "digital games are cheaper than physical now" strategy.