L.A. Noire

The best price for L.A. Noire is $5.63 at Difmark. That is 71% less than on Steam, where it costs $19.99. 9 shops have an offer that activates in your country.

Some are. This page only shows offers that activate in your country; offers for other regions, or with no stated region, are left out. To see the offers for another country, change your country at the top of the page.

That depends on the offer: each offer in the list shows the launcher its key is for. Redeem the key on that launcher and L.A. Noire stays in your library for good.

Yes, with a small risk. Publishers create keys to sell in other shops, which is why a key can cost less than in the official store, and once you activate it the game is yours to keep, just like a store purchase. On average 1–2% of keys fail, so check the shop's buyer protection before you buy: the official store does not refund keys bought elsewhere.

No. L.A. Noire is a single-player game.

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

Yes. L.A. Noire is the full base game. You need nothing else to play it.