Maybe not your case but theres D2 on the web (ie in your browser). You just load some game data to it, otherwise it is a demo until the first boss or so.

Link: diabloweb

Edit: yikes, made a mistake - its D1 not D2.

Quick search for “penn 3” tells me its indeed for tennis. Not sure about dog specific ones though, never heard of em.

Cute doggo!

Just a side note - those balls are quite bad for their teeth, as they wear them down like with a sandpaper.