The “Super Metroid/ALttP Combo Randomizer” run was pretty fascinating for me, because I didn’t know these combo randomizers even existed. Basically it shuffles all the items in Link to the Past and Super Metroid together into one big item pool and there are set points on the maps that will transition you between games. Sometimes you’ll need to find a specific item in Metroid to make progress in Zelda or vice-versa. Since the items are shuffled randomly between the two games the runners have to make a lot of routing decisions on the fly to try to beat the games efficiently.
They play it two player; one player plays the Metroid sections and one plays the Zelda sections. It’s sort of like a speedrun relay race.
Probably a bit too long for most people to watch, but watching part of it will give you a pretty good idea how it goes. Plus I think the two runners have pretty good chemistry; you can tell they’re pretty good buds.