I've been thinking about merging the difficulty categories as it doesn't really affect the times at all. For example, the Normal difficulty's time in the UNO subgame is lower than in the Hard difficulty's. All three difficulties are within 6 seconds of each other and you could probably match the Easy's time while playing on Hard. As for Skip-Bo, the difficulty probably changes the gameplay more than in UNO. I just think it's kind of redundant to have three categories that have the exact same gameplay.

I'd be fine with adding in 3 and 4 player categories along with the 2 player category like other UNO speedrun leaderboards.