- add the head to the vehicle
- move the head
- shoot
- show the bullet inventory

step 3 - there comes life

- add life bar to the alien
- add npc with life bar in map 1
- shoot the npc

step 4 - recycle

- add the bullets counter
- reduce npc life to zero shooting
- show dead sprite
- recyle to energy
- recycle to bullets

step 5 - levels please

- define levels map + npc positions
- code boss behavior for levels
- count the time used to finish each level

step 6 - polish

- add help screen

already done ...
step 1 - navigation

ok - show splash
ok - show map selection
ok - select each map
ok - press Esc to end the map and go back to map selection

step 2 - movement

ok - build map based on string of heights
ok - build the char (do i need to animate the bottom of the alien ?)
ok - move the alien around the map
ok - make the jump of the alien
ok . control the height of the alien with the colision with the ground.