Hi, thanks for your feedback. Its always good to hear that someone likes your work but it's always better to hear what people don't like or the things that can be improved and in this case there is still a lot to do on it and plenty of areas that bug me that need to be tweeked but i will get to them eventually.
In regards to your questions.
Two reasons why i didn't use the up arrow for jump.
1. If the player has to use both hands on the keyboard to play the game it's my belief that the player is more engaged with it ( less likely to go yada yada with one hand.
2. More importantly i keep this key free because later on i might want to add flying or overhead gameplay and it's much easier to not have it assigned to other controls. Generally i like to keep all character movements for all layouts on one data sheet.
As for the screen going black, this is just because it's a one stage demo. I could have set it to start over again but once you tested it i didn't see the need for more play on it. I have game over and start menus and stage select menus set up, but that's not for this demo as those menus are not ready.
thanks for your questions and interest