Working on a sample of 'bt' and 'st' together with 'ac'.

samples/.gitignore

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+setup.sh
+*.po
+!template.po

samples/mkships.sh

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+#!/bin/bash
+
+if [ ! -f ./setup.sh ]
+then
+  echo "This script depends on a 'setup.sh' script in the local directory."
+  echo "'setup.sh' should define an alias for 'bt' and 'ac'."
+  echo "Alternatively, you may craft a shell script with those names and place them on"
+  echo "the PATH."
+  exit 1
+fi
+
+shopt -s expand_aliases
+source ./setup.sh
+
+cp template.po ships.po
+bt --stdout --applesingle --optimize ships.bas | ac -as ships.po startup

samples/ships.bas

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+10 gosub 50000
+
+20 hgr
+30 hcolor=6:hplot 0,13 to 279,13
+
+100 hcolor=3:x=140:sd=0:s=sh
+110 dx=0:dy=0
+
+200 xdraw s at x,10:ox=x:os=s
+210 ky=peek(-16384):if ky > 127 then 300
+220 x=x+sd
+225 gosub 400
+230 if x < 10 then x=10
+240 if x > 270 then x=270
+250 xdraw os at ox,10
+260 goto 200
+
+300 poke -16368,0
+310 if ky=136 then s=sh:sd=sd-1:goto 399
+320 if ky=149 then s=sh+1:sd=sd+1:goto 390
+330 if ky=160 and not dx and not dy then dx=x:dy=15:ds=dc:xdraw ds at dx,dy:goto 390 
+390 if abs(sd) > 3 then sd = sgn(sd)*3
+399 xdraw os at ox,10:goto 200
+
+400 if not dx and not dy then return
+410 ax=dx:ay=dy:as=ds
+420 dy=dy+2:if dy > 160 then dx=0:dy=0
+430 ds=ds+1:if ds > dc+3 then ds=dc
+430 xdraw as at ax,ay
+440 if not dx and not dy then return
+450 xdraw ds at dx,dy
+460 return
+
+49999 end
+50000 $shape src="ships.st", poke=yes, init=yes, assign=(sb="sub-left", sh="ship-left", dc="depthcharge-1")
+ 

samples/ships.st

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+.bitmap sub-left
+  ....xxxx.......
+  .xxxxxxxxxxx.xx
+  xxxxxxx*xxxxxxx
+  .xxxxxxxxxxx.xx
+
+.bitmap sub-right
+  .......xxxx....
+  xx.xxxxxxxxxxx.
+  xxxxxxx*xxxxxxx
+  xx.xxxxxxxxxxx.
+
+.bitmap ship-left
+  .....xxxx......
+  .....xxxx......
+  xxxxxxx*x..xxxx
+  .xxxxxxxxxxxxxx
+  ..xxxxxxxxxxxxx
+
+.bitmap ship-right
+  ......xxxx.....
+  ......xxxx.....
+  xxxx..x*xxxxxxx
+  xxxxxxxxxxxxxx.
+  xxxxxxxxxxxxx..
+
+.bitmap depthcharge-1
+  xxx
+  x*x
+  ...
+  
+.bitmap depthcharge-2
+  xx.
+  x*x
+  .xx
+  
+.bitmap depthcharge-3
+  xx.
+  x*.
+  xx.
+  
+.bitmap depthcharge-4
+  .xx
+  x*x
+  xx.