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i_editor 2.0


I_EDITOR is a programming game. The goal is to write simple scripts to reproduce a drawing on screen. The commands used in the scripts move a pointer (“turtle”). The pointer has a pen, which can be up or down. When the pen is down, each move lays a print. There are additional instructions to make calculus, evaluate conditions and call previous declared sequences. The syntax and semantic are organized in language called I_CORE.

I_EDITOR 2.0 and its manuals are available as a PICO-8 cartridge (download the picture) and PDF files : english , french.

You can play the game online.

i_editor 1.5


. displays result in the drawing (up to 17 lines)

Sample 1
5 4 + .

Clipboard enabled (<CP, >CP)

CLR : clear
<CP : copy from clipboard
>CP : copy to clipboard

Copy the line below into the clipboard

:a 10 fd 90 tr ; a a a a

Paste in PICO-8, then activate <CP


Sample 2
:a >a # <a / flr # b >b <a * – <a 2 / flr # ?a ; :b cl 4 c ; :c 1 – # 3 fd 3 bd 90 tr 1 fd 90 tl ?c ; pu 20 20 mv pd 62 128 a pu pd 20 24 mv 127 128 a pu 20 28 mv pd 73 128 a pu 20 32 mv pd 127 128 a pu 20 36 mv pd 62 128 a pu 20 40 mv pd 42 128 a

Clipboard functions (<CP,>CP) aren’t working in HTML exported cartridge.
Copy from notepad (text in the html browser may contain tag or additional characters).



Choose the command in the first column (up/down, x)
Change column (left/right)

Change the value in the second colum (x, then left/right to decrease/increase)
Delete instruction in the second colum with (o)

Have a look on i_core post to have more explanation about the language “I”.

I will make a tutorial soon and post a link and additional information here.

Sample 1 (gif)

:A 20 FD 90 TR ; :B 1 – # A ?B ; 4 B

Sample 2 (gif) made by roywig



You can accelerate the rendering process in the M:DRAW method. At the end, change from



while i>0 and self.vm:state()!=3 do

i_core + turtle


This cartridge includes i_core and the turtle extension.
It shows how to:
– bind a personal extension (turtle object, turtle binding) to the language core engine,
– initialize the external extension and call its methods (from PICO-I and i_core)
– pass parameters from PICO-8 to i_core (N).

The turtle extension includes the following commands:
– FD forward, 20 FD
– BD backward, 20 BD
– TR turn right, 90 TR
– TL turn left, 90 TL
– CL change color, 1 CL
– PU pen up, PU
– PD pen down, PD
– TO go to, 10 10 TO
– HD head to (0 right, 90 top, 180 left, 270 down), 0 HD

Sample :

‘:loop 20 fd <a tr 1 – # ?loop ; :side >n 360 <n / >a <n loop ; cls 4 side’

Have fun 😉






This is the core engine of a language (‘I’) and its virtual machine (all of this in PICO-8).
You can extend this engine (see how _SHW or _CLS are implemented).
You can create synonyms for a simplier use (see _ADD and _+).

The programs must be writen in a line. Terms are separated by space.

The engine is stack based (like forth): ‘5 4 + .’ => shows 9

The operators + – * / and flr function are available.
The ‘#’ duplicates the last value (of the stack).

You can evaluate (5 + 4) * (3 + 2) with ‘5 4 + 3 2 + * .’ => 45

Create a sub function

:NAME <sequence of instructions> ;

‘:A 5 4 + ; :B 3 2 + ; A B * .’ => 45

You can call the sub function NAME with its NAME (see A and B in the sample).

Create SQUARE and evaluate 3^2:

‘:SQUARE # * ; 3 SQUARE .’ => 9

Conditional call


If the last value in the stack isn’t zero it calls NAME else it goes to the next instruction.

This is usefull to create tests and loops:

‘:SA # . 1 – ; :LP SA # ?LP ; 5 LP 0 .’

Count down from 5 to 0 (then stop).

You can use variables:
>NAME (load value from stack)
<NAME (push value in the stack)

‘1 >A <A <A + .’ =>2

You can use many :EVAL call to enter your program (one line per call).
You can use as many i_core engines as you want at the same time (object).
You can execute the whole program (:EXEC) or run it :STEP by step.

:STATE returns 3 when done. You can restart with :STATE(0).

If you have read the description so far, you may have a question.
This sounds crazy… So, why?

I’m working on two games. In the first you have to build a program by stacking graphic items to draw on screen to replicate a drawing with the minimal amonth of items. In the second, some robots fight together using genetic algorithms to evolve (by sharing part of their own code to create new ones).

I think I can share this library and my interest in doing this.



VCT from PICO-8 to Monkey2

For the PICO-8 Jam#2, I have done a game : “VCT”. You can play it here or download the cartridge (below).


Now, I’m working on a enhanced version using Monkey2. The first step was the translation of the main methods :  _init, _update and  _draw. For this, I have made a basic version of the VCT “engine” (which uses vectors to  draw and animate) with pico-8. You can use left, right, up keys (or a gamepad) to test. The cartridge and explanations are available (or will be soon)  in picozine#5.


Then I started to write all the required stuff to produce the same with monkey2. The result is pretty good. I have to polish the switch between full screen and window mode. You can download and compare : windows binary (auto-extractible).

Right now, I’m sure Monkey2 is the good tool to go further.
Stay tuned, I’ll post updates in the next coming weeks about this.


After spending some months, working on and not updating codyssea, I’m back here. I have discovered a new great language done by Mark Sibly : Monkey2.  It’s free, opensource and fully fonctional. I’m working on the translation of a game made with pico-8.