Jumper XLN (MSX) by Raul Portales

# Jumper-XLN

Your gola is to reach the riht side of the screen jumping using the spacebar

## About the program

It's been a lot of juggling to make it fit in the PUR-80 category

First, the sprites are defined as strings, which limits them to the range of

printable ASCII characters, that made designing the assets for the game a bit 

more challenging.

Given the limitations I opted for SCREEN 1,3 as the mode. Screen 1 allows us to

draw text on the screen as well as sprites, the second parameter indicates to

use 16x16 sprites magnified. I would normally discourage such setting, but

given the limitations I wanted the characters to be large.

The sound for the jump is done using the SOUND command, which works instantly,

instead of PLAY, which is used for the game over and win tunes. PLAY will freeze

the computer while reading the tune, and that will kill gameplay. Using SOUND

for the jump was necessary. The jump sound also uses the envelope function of

the PSG, which is not used on the other tunes, for that I needed to use a

different channel for each (tunes on channel 1, jump FX channel 2)

The game also waits for the music to finish before you can start a new game.

3 IFNOTSTRIG(0)ORPLAY(0)THEN3

Of course, I removed all the spaces that were not necessary to allow for more

characters, and used single numbers for the lines (all that are obvious tricks)

lines 1 to 3 are initialization, spread to not go over 80 columns

line 4 is the check for new game (and extra initialization)

line 5 is the check for the jump action if not already in a jump

line 6 is the draw of the player and the update of all the variables

line 7 and 8 are the draw of the obstacles and their update

line 9 is the check for winnging or return to game loop (line 5)

line 10 is the sprite collision handler, and display of game over