I'm thinking of building a simple game like this(but not with shooting stuff) using node on the server side since it's the cool thing to do now. But idk how man

I'm thinking of building a simple game like this(but not with shooting stuff) using node on the server side since it's the cool thing to do now. But idk how many players a server could sustain or if the browser client might slow down when rendering many players on the screen. Anybody want to help? Should just take about a week to build something playable i think.