#correction: web browser with HTML5 <canvas> capabilities. You'd be hard-pressed to find a web browser without though.

[sa-game-remake]

Is there a version I can download on my iPad?

Of the old game? If you downloaded the game in the past, you can go to the Purchased tab of the App Store and download the app again. There's some evidence that either new devices or new iOS versions don't play nice with it, so it's not guaranteed it'll open and play.

Even then you can only play on Guest mode (no multiplayer, only one character). That's inevitable since the main servers no longer exist, so there's nothing to log into or anything to organise multiplayer.

Of the remake? It's not playable yet, but since it'll be a website (most likely game.keeperofgreenhaven.net), it should be playable from any device that has a web browser.