Angle Restrictions

Names/terminology used here are placeholders and not necessarily official/final

Normal (no key restrictions)
- Maybe includes backwards as a subtag (need to figure out what the criteria for "backwards" is though)
SW (W+S)
- Could include left/right direction only as a subtag
Surf HSW (WA+SD or WD+SA)
- Could include backwards as a subtag

Bhop HSW (WA+WD / SA+SD / WA+SA / WS+SD)
Other (W+A / W+D / S+A / S+D)
- These aren't really a thing but it works the same and would go in this group

Notes

Each group is its own leaderboard, and within each leaderboard, each run could be tagged with what specific restrictions that run claimed to have (the only thing that can be verified is which group the run should go in, beyond that the client can fake angles or whatever). You could filter to some specific tag(s) when browsing, but as far as ranking/points goes, there can be no finer breakdown than just these 3 groups.
Each group is progressively more restrictive, so there should be one leaderboard with A+B+C, one with B+C, and one with just C. It's important to rank more restrictive runs against less restrictive ones, because a run might be rank 2 out of 2 in Group C alone, but appear much better when stacked against all runs combined.
I am really not sure how points/ranking factors into all this. Maybe there needs to be a way for a run to earn points for all leaderboards it qualifies for, but I don't know exactly how that would work. At a minimum, a run should earn points for the least restrictive leaderboard it qualifies for. If we can figure out a way to go beyond that without it also being endlessly complicated to implement and understand, all the better.
Technically you could even have 45 deg (e.g. A+WD etc) and 135 deg (e.g. W+WA etc) groups but that would be a bit silly

The player should be able to choose which of these to run as before they start and the game will apply the necessary restrictions
Some community servers on other games don't impose angle/key restrictions initially, but determine which mode the player is trying to run based on their inputs. We could have this as a second method but it shouldn't be the only one.
Basically the player should have the option of having their client explicitly impose restrictions when playing, but the final mode/tags determination would be done independently by the verification backend. Additional tags that the player didn't explicitly select could be added to the run at the time of verification if the run qualifies for them.

Modes which alter gameplay need to be on a separate leaderboard, and each could even be broken down into Groups A/B/C as above. These would be even more niche though which is another reason why its important to factor runs into all less-restrictive leaderboards they also quality for.
Modes which we carefully determine to have a strictly linear relationship to other modes in terms of difficulty could be nested together similar to the angle groups listed above. For example, a segmented mode is a strictly easier version of normal gameplay, so a segmented leaderboard could/should also list non-segmented runs. Low-grav on the other hand is usually easier but is sometimes more difficult and therefore could not be stacked against with normal runs.