Landing

Rules

Land rocketship safely on moon surface. Engines produce their maximum thrust when up arrow is pressed. Watch you fuel -- you have only limited supply.

If landing speed is too high, the rocket will explode () and if rocket speed is not high enough to explode, but still high, it will turn into unusable pile of junk (). In any case you can hit space key to try again.

Code and comments

This is the first game in the series (and the only remaining, if lost VETKA.NSG is excluded) that works in graphic mode (SCREEN 2).

There are no breakthrough technologies involved, just several small tricks here and there.

• Extremely powerful and compact DRAW operator draws background scenery and instrument panel.
• Sprites are used for rocket, engine flames, explosion and pile of junk.
• Sprite definitions as string are written in most compact form -- as literal strings. I tried to draw them in a way that they can be encoded with as many printable characters as possible.
• Fuel bar is 2 pixels wide, but when fuel is used only one PSET operator is used to update display. This is due to peculiarities of SCREEN2 graphics.
• Once again, comparison operators are used in arithmetic expressions to reduce IF control structures
• U=SIN(10) acts as a delay -- without it explosion flash happens too fast to be noticed.
• MSX BASIC processes FOR U=0 TO 0 STEP 0 as infinite loop that will run forever.