Here is also a website where you can see if there is an open source port to non-open source games or an alternative that e.g. tries something of its own / based on the gameplay. As an example, the following "clones" are listed for Minecraft: Minetest, Mineclone2 (now VoxeLibre), ManicDigger and more.

Edit: fixed some grammatic fails.

To name a few: AssaultCube, Battle for Wesnoth, Cube2: Sauerbraten, FligthGear, Freeciv, Freeciv21, Nexuiz Classic, OpenArena, OpenHV, OpenRA, OpenTTD, Remnants of the Precursors, SpeeDreams, Stone Kingdom, SuperTux, SuperTuxKart, Unciv, Urban Terror, Veloren, Warozone 2100, Widelands, Xonotic

P.S. It may be that not all of them are FOSS, but they run natively on linux.

I also don't know why Mojang/Microsoft handles it this way. They could make it available by next year, because I don't think Minecraft has another birthday this year where there's another cape. I'm keeping my fingers crossed that you can still get the Cape.

Yes, I got the link from the waybackmachine. I went to the link and then right-clicked on the Sing in to Claim button and then copied the link, pasted it here and then removed the waybackmachine stuff so that the link is the original link again.

The link I sent, I also got from the waybackmachine. I also see the page with the tickets without a waybackmachine. Then it is probably no longer possible to get the cape. It's a real shame that Mojang / Microsoft run fomo. There are now two options left for you. 1. Politely ask the Mojang support about the cape. 2. Ask on other platforms if anyone still has a code for the cape (If there was a code at all, I don't remember if it wasn't just added to the account).

This is the Link that was embedded in the Sign in to Claim Button. Maybe it still works: https://www.minecraft.net/en-us/login?view=msa&return_url=/15th-anniversary?mcRef=redeemCape

I would like to give it away, but I would wait for the answer from @DreitonLullaby@lemmy.ml, if there is also interest. Do you already have a cape? And it's not clear whether the code really works.

I received two TikTok codes and I don't know if the second one really works. It says that it expires in two days.

There are three capes. The 15th Annivesary Cape, Twitch Cape, TikTok Cape and a Twitch Hat or something like that. Do you have one of the others, or are you only interested in the 15th Anniversary Cape?

The Half-Life Games.