HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

Either I'm so stupid that I don't use it, or the opponents are too smart, but by the end of the game, I always have a lot of time left, while the opponent has almost none!
And tell me, is there a difference between the 4000 I have left and the 130 the opponent has? It's not always such a big difference, but there's always a significant amount remaining.

Such a difference can arise simply because one person clicks the mouse at a different speed. Everyone plays at their own pace, with their own keypress speed, etc. If someone takes longer to make a move, it doesn't mean they're thinking longer or are less intelligent. It's just that the opponent is more comfortable playing at a slower pace. A simple example: Player 1 takes half an hour to play a game week, while Player 2 takes an hour. And then Player 2 complains about the timer. In principle, Player 1 could have played faster, but they don't, because they don't like to rush. The process is more important than clicking quickly. And besides, don't compare your abilities to others. They may simply be different. And what difference does it make how much time the opponent has left on the timer? If it's given, it means you can spend it all. It's easier to play with 1000+200 then.