The short answer
A game listed at 100% off (also shown as "Free to keep" or "Free to play for a limited time — keep it forever") is a normal paid game with a temporary discount that takes the price to zero. If you add it to your account during the promotion window, it is yours permanently, exactly as if you had bought it. When the promotion ends the price returns and the game stays in your library.
The catch is that you have to actually claim it. Wishlisting it, adding it to your cart, or bookmarking the page does nothing. The transaction has to complete — you press the button, the store processes a zero-value order, and the game appears in your library.
Three things that look similar
Steam has three different kinds of "free" and they get confused constantly.
- Free to play: permanently free by design, no claim needed, monetised in-game.
- Free weekend: temporary full access, ends when the event ends, you keep nothing.
- 100% off / free to keep: a limited-time offer to own a paid game permanently.
Does it count as owning the game?
Yes. A game claimed at 100% off sits in your library like any other purchase. It receives updates, it counts toward your library size, achievements work normally, and if the game supports Steam Trading Cards, card drops work the same way they do for a game you paid for. Free-to-play titles are the ones that behave differently on cards, not free-to-keep promotions.
One thing it does not do is lift the limited-account restriction. Steam considers an account "limited" until it has spent a qualifying amount of money, and a zero-value order does not count toward that. If you are on a fresh account, claiming a hundred free games will not unlock trading, the Community Market or friend invites.
Restrictions to expect
Promotions of this kind are almost always time-boxed, often to 24 or 48 hours, and the window is enforced strictly. Some are also region-limited, so the offer may not appear in every country. Occasionally the free item is a specific edition or an older entry in a series rather than the current release, which is worth checking before you assume you are getting the flagship title.
Refunds are not a factor since nothing was paid, and there is no downside to claiming beyond the disk space you use if you decide to install it. Claiming is always worth it: an unclaimed free game is simply gone once the window closes.
Where these promotions come from
Publishers run them for a few predictable reasons. A studio launching a sequel may make the previous game free to build an audience, a service game may go free to keep to grow its player base ahead of a season, and older catalogue titles are sometimes released free as goodwill or to mark an anniversary. Some coincide with seasonal sales, others appear with no warning at all.
Because the windows are short and unannounced, the practical difficulty is noticing them in time. Storefront front pages rotate quickly and a 24-hour offer can be missed entirely by anyone who does not check that day. That is the problem a tracker solves — the Boostr free games page follows Steam alongside Epic, GOG and Amazon so that the claim window is caught rather than discovered afterwards.