ronny14, thanks for your advices! I'll do everything what I can to fix this. I even didn't noticed most of this details, I think I should be more inspective for things like this.
Jorge D. Fuentes I already used "stop points" system with the stairs. When you press any directional button just once, character will move to one stair (8pix to both vertical and horizontal) and finishes his one-step animation. Anyway, I'll try to implement full-animation cycle, as you advices.
Oh, and one more thing! This video in 30 fps, but my game runs with the full 60 (sorry, I'm just decoded video that way), so there is some frames missing. I'll make a next video with some new features soon, I'll try to make it 720p60. Also, I have some webm videos (some of them are 60fps), Is there any way to post them here?
The jump animation... Things there can be little complicated, because of the way, how I have already done it. I hope it's not lethal, if It ended up with my current animations, but I'll really try to do something.
Rudolph LagnaGaisaer, thanks for the advice, but I already used a little different system. I have one special block, where in the beginning of the stairs and one another in their end, that's all. Also, I have never used sprite as an static game object (like stairs, floor, etc). In the attached picture you can see my dev-mode. And the special room transition isn't really the ROOM transition. It's still the same room, just with the camera movement blocked before the transition. Actual room switching always done the old way, with the simple fading in black before the room switch. I've already learned and using this technique, just didn't show it yet.
uzo, thanks, but... Nah, this isn't actually my own game design, I just looking at the official games and trying to do something very simillar, but still different. So I can't say it's my own design and as the whole game - It's just a rip-off with some of my own ideas.