Super easy to compete with steam on your own game store.

You can buy your games here, for the same price you can buy the physical disk. It's the same game you would get if you bought it anywhere else. We guarantee your games will be here forever, and if they aren't, then we'll make them playable offline before we shutdown.

Nothing else needs to be done. You don't need to make your games unplayable from other vendors, you don't need to add specific rewards for using your storefront. All people want to do, is buy their games, and have a right to play them.

Hence the meme where every digital storefront is shooting themselves in the face while steam looks on with concern.