OOTP

 https://www.reddit.com/r/baseball/comments/5q47k7/hi_reddit_i_am_markus_heinsohn_developer_of_out/
https://theathletic.com/4339875/2023/03/24/out-of-the-park-baseball-24/

https://forums.ootpdevelopments.com/showthread.php?t=88412

https://www.si.com/extra-mustard/2014/08/08/interview-creator-out-park-baseball

Fictional leagues:

https://skylinebaseball.org/

https://forums.operationsports.com/forums/baseball-dynasties/1000189-baseball-worlds-game-ootp-22-fictional-world.html makes it world-wide

https://www.cjohnsonphoto.com/metros/about.html explan of how he uses "import historical players" to create new players

https://www.fanbyte.com/legacy/players-are-building-their-own-fictional-worlds-inside-sports-simulators