...Percentage-wise.

By downtime I mean the following:

1. Loading times.
2. Cutscenes
3. All sorts of "Item obtained" poses.
4. Menus and dialogue popping up.
5. Screen transitions.

etc.

Flash games but that's probably not what you were thinking

---For low loading times, I suggest highly optimized PC games ran on a powerful PC. But there are obviously console games from all generations that had little to no loading times. ---Cutscenes truely depend on the game. For instance, a game could have 30 minutes worth of cutscenes, but if they are skipable, it doesn't matter to a speedrunner. But compare that to a game with 5 minutes of unskipable cutscenes. Those 5 minutes will be considered downtime. ---To avoid "item obtained" poses. Try to avoid RPG's, collectathons, and metroidvania type games that have key items. Again, not a rule, but generally considered true. ---Menus and dialogue are dependent on the game just like cutscenes. However, games that use keyboard controls have access to more keys than console controllers. So it's possible that through having more bindable keys, there might be less menuing. But this is not a rule in any way. Truely depends on the game. ---Screen transitions are just loading screens with an animation.

Some of these things don't appear in a game at all. So it's hard to categorize downtime of entire genres or series.

Could you be more specific?

I can think of a couple off the top of my hand that have 0 sec downtime. Granted, they are like seconds long, so.

And how do you measure downtime? in many games, you can only input commands once per frame maximum. So is the time between frame perfect button presses considered downtime?

Portal elevators mod on an SSD. Pretty much only one downtime that's longer than 0.1secs.

Tetris is the first thing that comes to my mind. It has none of those things.

Super Mario Bros 1/2/3/World (although some of those have level select screens).

Sonic 1/2 (3 and Mania have cutscenes although for 3 it might just be the opening one; CD has time travel screens but I don’t think an any% run would come into contact with them). 1 has some super slow segments though, so 2’s probably your best option there.

I think Freedom Planet has a mode where you skip all cutscenes and just play through the levels.

Sonic Heroes. It does have some short cutscenes and fair loading times, but the levels are much longer than the average Sonic game (especially for team Dark) and there are fun glitches and skips littered thoughout the entire game. The most common category is any% because the True Final Boss has a 43 second transformation sequence.

Gutar Hero/Rhythm Heaven? They can’t really be speedrun, per-say, disregarding menus, but you might want to look into all-perfect runs.

Mario Odyssey’s a decent one. There’s sadly a little downtime at the very beginning and I’m not sure the credits are skippable if you want to do 100% runs (although I think given how long that’d take you’d be glad for the break).

Not to mention the ever-classic Mario 64. Sunshine has a really long cutscene right at the beginning though.

Pacman.

The original Legend of Zelda. Also BotW, in a similar fashion. Very few cutscenes are necessary in either of them. BotW any% is a very short run though, so I wouldn’t recommend buying it just to run that category.

Sandbox games like Minecraft/Terraria. Not Starbound, that has a few reaaalllly long unskippable cutscenes which I find endlessly annoying in an otherwise amazing game.

Mario Kart. I’m not sure if the start-of-race and final-placings cutscenes are skippable in all the games, but I think they are in most.

I haven’t played it in literally 10 years+, but I seem to remember NFS: Most Wanted (the PS2 game) being good about cutscenes. In fact I just checked and it seems that only one of them unskippable - the any% WR if almost 4 hours though, so you’d be in for the long haul.

Portal 1/2. 2 has a fair amount of dialogue, but you can still move while most of it’s in effect so you can try out some cool tricks in the meantime. 1 has less dialogue but I don’t think it’s as fun a run overall.

That’s all I can think of for now, hope it’s a good starting point.

Resident Evil 3 for PC allows you to skip the cutscenes AND the door loading sequences (and afaIk is the only RE to let you skip both). Watching good RE3 runners is fun bc its just non-stop movement and dodges. You do have to perform a fair bit of menuing, but it can go fast if you know what you're doing. Lol

Actually, I think Super Mario Odyssey has way over 2 hours of downtime ( for 100% run.) and at least 10 minutes of downtime in any% run. I'm counting the Mario grabbing a moon, a moon being spawned, small unskippable cutscenes etc.

Oh...Jazz Jackrabbit has less downtime than Sonic 1, 2 and 3 because of shorter score counter at the end of the level.

One game I found to have very little downtime is Dustforce. Less than 3 seconds per level the most.

GTA 3 only has a little bit of waiting. Sonic (gotta go fast, duh) Portal if you're really good is extremely fast Mario for sure

Boktai 1 & 2 barely have any downtime Resident Evil games (atleast the old ones, like 3 and 2) on PC barely does too, since you can skip almost everything. I think Dino Crisis PC works just the same also.