Thank you, GNU, you have already brought much to the game, and I know you know what an original arcade game is ! You're right when you say nowaday's video games are mainly about short games with lots of lives and restart from any level already unlocked. Seems likes people have absolutely no time for anything today ! Hop!2D would be really easy to adapt to cell phones (low resolution, very few controls) but the more I think about it, the more I wonder if people would be patient enough to play a whole world. One more reflexion to have, I guess...
Talking about training system, I'm not sure of anything right now. I'm quite happy with HELP menu (I tried to get the right balance between completeness and concision) but I understand some players need something more dynamic. I often said world 1 was already designed as a training world and I still believe it. I may add some indications to help the player but the main thing is about handling Hop's movements and jumps. Some complains I had were about depleting energy. It seems some players are not comfortable with it even in the first levels, they don't feel they're actually training with the threat of losing a life.
If I happen to design a "real" training level, I'd like to make it more interactive : for example, a door to next section of the level opens only if the player has completed the current goal (move left and right, accelerate, reach a platform, jump over an obstacle, etc.). And of course, nothing about energy, enemy or more advanced mechanisms, just the basics. I admit I had Portal in mind while building the game, I liked the idea of a tutorial included into the game itself.
One last thing about hitboxes : I have already modified most of them in the incoming BETA 21 version but the main goal was not to make the game much easier than it is. Just to make it less "touchy" in some tight situations where pixel-precision was not really needed. From what I have tested, changes are not huge but the feeling of a close call instead of a "game over" may be the one reason for some players to stick to the game. Nothing is changed for Hop, modifications are about everything else.