The other day I realised how long I'd spent in the Dota-verse. It was during my 50th hour of Dota Underlords, after 100 hours of Artifact and nearly 4000 in Dota 2. There are characters I have spent years with, albeit while treating them more as clusters of abilities than personalities. I've seen that world from half a dozen different angles, over the years, between genres and Dota 2's seasonal events. It means something to me. I'd be very interested if Valve announced they were inviting other developers to make games set in the same universe.
Valve haven't, but that's exactly what Riot have announced they're up to with League Of Legends. I know next to nothing about League and have little desire to explore more of Runeterra, but it's easy for me to imagine people feeling otherwise.
Multiple titles are already in development, according to the press release, to be published under the label "Riot Forge". These will "focus on developing completable game experiences", as opposed to live multiplayer stuff.
That's it for details, apart from some bluster about how Riot are excited to work closely with their new partners to exploit League's "limitless potential with its expansive world and deep champion pool".
It would seem they truly do think League's potential is limitless, after announcing in October that they're making four other games based on LoL - plus an animated series, in addition to the comics they've already published. I hope both the world and its creators don't get too tired.
Getting other folks to make stuff might be a way around that, especially if they head off in different directions. With Riot's in-house games alone, in the next few years you'll be playing wizard CCG Legends Of Runeterra, punching wizards in a fighting game codenamed Project L, managing non-wizard wizard manipulators in LoL Esports Manager, and possibly moseying around on some kind of wizarding action adventure codenamed Project F.
That leaves about four genres unexplored. Bring on the Runeterra Zachlikes.