Heroes 3: Complete Edition crashes very often

Download and run the installer. Then, launch the launcher, and in the launcher window, set the desired parameters (you don't have to change them). Check the box in the "No CD/DVD" field. I also download and add a Russian superpack, which changes the fonts and texts to be more convenient (than in the "Complete Collection"). On the "Tweaks" tab, I also set Sys.CPU.ReduceUsage = 1 (reduces CPU usage, but may not be suitable for those with gaming mice that have a very high polling rate for cursor coordinates). Another useful option there is UI.Tavern.InviteHero = 1, which allows you to invite (find) a desired hero from the available ones in the tavern.
The HD+ option includes bug fixes for the game, but it also introduces some effects that are important for single-player maps: it changes the arrangement of obstacles on the battlefields.