someone sent you a hamster

It lives on your screen. It has something to give you first.

Apple silicon Macs (M1 and newer) · 100 MB

Setting it up

Open the download
Double-click Hammies.dmg in your Downloads, then drag Hammies onto the Applications folder next to it.
Tell your Mac it's okay
This was made by one person for one person, so Apple doesn't know it. Open the Terminal app, paste this, and press return:

xattr -cr /Applications/Hammies.app

Nothing prints; that means it worked.
Open Hammies
From Applications or Spotlight. It asks who's at this computer. Pick yourself.
Read what it brought
Then press the last button and let it in.

Click it to pet it. The person who sent it feels that.
Drag it somewhere else if it's sitting on something you need.
Hover over it to see what its owner is up to.
The hamster icon in your menu bar opens the remote for your hamster, which lives on their screen. Alt+Shift+H does the same.
That same menu can hide it for an hour, mute it, or stop it from telling them which app you're in.