Grapple!

Yes. Grapple! is free to play on Steam, so there is nothing to buy to start playing.

The minimum requirements for Grapple! are: Windows 10, Intel UHD Graphics 620, Intel Core i3. It runs on Windows only. The recommended specs are in the System requirements section.

No. Grapple! is a single-player game.

Mostly, yes. Valve rates Grapple! as Playable on the Steam Deck: it runs, but may need some manual setup.

Yes. Grapple! is the full base game. You need nothing else to play it.