I have made a studio on Scratch with projects related to the FORTH programming language:
https://scratch.mit.edu/studios/3675667/

This studio is mostly interesting to those who study computer science.

The project there that I developed myself is Starting FORTH Calculator Screen Keyboard:
https://scratch.mit.edu/projects/137676871/

It's not a game, but you can write games in it.


Instructions
Shift+click a green flag to start Turbo Mode, then click a green flag. It first runs a demo with graphics and sound at the end.

The FORTH programming language is good for embedded systems and is used in successful deep space missions, radio astronomy, and medical devices. This simulates a retro computer like e.g. Jupiter Ace, or ZX81 with ZX-FORTH from the early eighties. For these old computers FORTH was usually the fastest high level programming language/integrated development environment (IDE) available. http://www.forth.org/successes.html

Type using these keyboard keys (due to Scratch limitations):
0-9, A-Z = types key. FORTH is case insensitive.
Arrow right = Full stop, <.>.
Arrow left = Backspace, <BS>.
Arrow down = Carriage return/Enter, <CR>.
Arrow up = Shift - pressed before 0-9, A-Z, <.>, <SPACE>, <CR>.
Shift+J = -. Shift+K = +. Shift+B = *. Shift+V = /. Shift+M = >. Shift+1 = !. Shift+2 = @. Shift+I = (. Shift+O = ). Shift+P = ". Shift+Arrow right = ,. Shift+Z = :. Shift+X = ;. Shift+C = ?.
Shift+A = Ask – this makes copying from a tutorial and pasting into Scratch possible – typographical quote-characters from pasted text are converted to ASCII.
Shift+SPACE = Break.

The keyboard layout is inspired by SPONZY – a ROM for ZX81 which makes that computer ZX Spectrum compatible (Speccy on Zeddy).

If you run this on a device w/o keyboard, you may use the screen keyboard by clicking the blue keyboard in the upper right corner (same as Shift+A / Arrow up+A).

You can hide the stacks by going inside and click the check-boxes for the lists in the category Data.

The error codes are explained in: http://lars.nocrew.org/dpans/dpans9.htm

Examples (press <CR> i.e. arrow down after each command):
WORDS – Lists all commands.

.KEYB – Prints the keyboard layout.

: QUADRATIC ( a b c x – n ) >R SWAP ROT R@ * + R> * + ; 2 7 9 3 QUADRATIC .<CR> – Computes a*x^2 + b*x + c, where a=2, b=7, c=9, x=3.

: GIFT .” chocolate“ ; : GIVER .” Mum“ ; : THANKS CR .” Dear “ GIVER .” ,“ CR .” Thanks for the “ GIFT .” . “ ; THANKS

: FACT ?DUP IF DUP 1 - FACT * ELSE 1 THEN ; 7 FACT .

: STAR 42 EMIT ;
: STARS 0 ?DO STAR LOOP ;
: MARGIN CR 25 SPACES ;
: BLIP MARGIN STAR ;
: BAR MARGIN 5 STARS ;
: F BAR BLIP BAR BLIP BLIP CR ; F

All characters:
: .charset 1 do i emit loop ; 288 .charset

: .matrix ( r c – ) swap 0 ?do cr dup 0 ?do .“ (” j 1 + . .“ ,” i 1 + . .“ ) ” loop loop drop ; 5 3 .matrix

Mutually recursive functions:
: EVEN? ;
: ODD? ( +n – true | false ) DUP 0= IF EXIT THEN 1 - EVEN? ;
: EVEN? ( +n – true | false ) DUP 0= IF 1 - EXIT THEN 1 - ODD? ;
This is not standard FORTH, but simpler, because this FORTH currently uses the latest definition of a word during run-time.

Function pointers:
: COUNTS ' ROT ROT 0 DO OVER EXECUTE LOOP NIP ;
: CONVICTED-OF ( – no-sentence ) 0 ; : ARSON ( sentence – sentence+10 ) 10 + ; : HOMICIDE ( sentence – sentence+20 ) 20 + ; : BOOKMAKING ( sentence – sentence+2 ) 2 + ; : TAX-EVASION ( sentence – sentence+5 ) 5 + ; : WILL-SERVE ( sentence – ) . .“ years ” ;
CONVICTED-OF BOOKMAKING 3 COUNTS TAX-EVASION WILL-SERVE

Extending the compiler, example from: https://rosettacode.org/wiki/Extend_your_language#Forth :
: BOTH postpone IF postpone IF ; immediate : ORELSE postpone THEN postpone ELSE postpone IF ; immediate : NEITHER postpone THEN postpone THEN ; immediate :
fb ( n – ) dup 5 mod 0= over 3 mod 0= BOTH .“ FizzBuzz ” ELSE .“ Fizz ” ORELSE .“ Buzz ” ELSE dup . NEITHER drop ;
: fizzbuzz ( n – ) 0 do i 1+ fb loop ; 100 fizzbuzz

: STRING CREATE ALLOT DOES> + ; 5 STRING VALVE
3 VALVE C@ .

I have made some new videos about this FORTH programming language and a FORTH playlist:

1. (old) https://youtu.be/VZfUFnioLko 1 min <– Dec 26 2016
2. (new) https://youtu.be/FwEgRetggFg 1 min <– Feb 2 2017
3. (new) https://youtu.be/tPk1nNgq6NE 1 min
4. (new) https://youtu.be/tZOYPTv77pI 1 min
5. (new) https://youtu.be/nr0c87lrC64 1 min

https://www.youtube.com/playlist?list=PLD8D8534DD63B28EA

Please report bugs and test-code in the comments!


Notes and Credits
It's called #MOBLuSE_FORTH.

FORTH: https://en.wikipedia.org/wiki/Forth_(programming_language)

The goal is to be compatible with the book Starting FORTH by Leo Brodie:
https://www.forth.com/starting-forth/ . I have now tested it with chapter 1-2, 3 (except disk) & 4-11 (except strings and formatted number printing).

Jupiter Ace was a computer with FORTH built-in:
https://en.wikipedia.org/wiki/Jupiter_Ace . This program should have a Jupiter Ace compatibility mode. Also for ZX-FORTH for ZX81: http://zx81.ordi5.free.fr/k7/k7.htm . Also for ANS FORTH: http://lars.nocrew.org/dpans/dpans.htm .

Works in Phosphorus, but w/o showing stacks as lists:
http://phosphorus.github.io/#137676871
http://phosphorus.github.io/app.html?id=137676871&turbo=true&full-screen=true

Used Tosh as editor: https://tosh.tjvr.org/ . I also used Scratch 2 Offline Editor for debugging. I use FORTH-code from @BookOwl's Scratching FORTH in the sprite Compiled for testing: https://scratch.mit.edu/discuss/topic/213122/ .

TODO: IF with empty stack, answer to exercise 4-5 in Starting FORTH, editing command-line, history, all Scratch-commands, INCLUDED, screens, rest of the words from Starting FORTH, optimizations e.g. stack-compression, bit-wise operators e.g. https://scratch.mit.edu/projects/18323862/ .

Rules for programming FORTH: ftp.rssd.esa.int/pub/Cluster/directory/PP/Software/LSE_SW_Development/LSE-FORTH-Coding-Rules.PDF

Books about FORTH:
https://www.jupiter-ace.co.uk/index_forth_books.html


#MOBLuSE_FORTH 0.11.2 WORDS
<
=
>
?
-
,
;
:
!
/
.
."
'
(

@
*
*/
+
+!
0<
0=
0>
1-
1+
2-
2/
2*
2+
2DROP
2DUP
2OVER
2ROT
2SWAP
ABORT
ABORT"
ABS
ALLOT
AND
AT-XY
BEGIN
BELL
BL
C!
C@
C,
CELL+
CELLS
[CHAR]
CLEAR
COLOR
CONSTANT
CORE
CR
CREATE
DIR
DO
?DO
DOES>
DOWN
DROP
DRUM
DUMP
DUP
?DUP
ELSE
EMIT
ERASE
EXECUTE
EXIT
EXT
F/
FALSE
FLOOR
FORGET
FROUND
GOTO-XY
HERE
HUE
I
I'
IF
IMMEDIATE
INSTRUMENT
INT
INVERT
J
K
KEY
.KEYB
LEAVE
LOOP
+LOOP
MARKER
MAX
MIN
MOD
/MOD
*/MOD
MOVE
MS
NEGATE
NIP
OR
OVER
PAGE
PLAY
POS@
POSTPONE
QUIT
>R
.R
R>
R@
REPEAT
REST
ROT
-ROT
R.S
.S
SHADE
SIZE
SPACE
SPACES
?STACK
SWAP
TASK
TEMPO
THEN
TIME&DATE
TIMER
TRUE
TUCK
U<
U>
U.
UNTIL
UP
U.R
VARIABLE
VOL
WHILE
WORDS
X
Y


Words in Starting FORTH main text that are missing in #MOBLuSE_FORTH
<#
[
]
\
#
#>
2!
2@
2CONSTANT
2>R
2VARIABLE
ACCEPT
AGAIN
BASE
BLK
BLOCK
CMOVE
CMOVE>
COMPARE
COUNT
CP
D<
D=
D-
D.
D+
D0=
DABS
DECIMAL
DMAX
DMIN
DNEGATE
D.R
DU<
EMPTY-BUFFERS
FILL
FIND
FM/MOD
HEX
HOLD
>IN
INCLUDED
LIST
LITERAL
LOAD
LSHIFT
M*
M*/
M+
>NUMBER
OCTAL
PAD
REVEAL
RSHIFT
#S
SCR
SIGN
SM/REM
SP@
SP0
TIB
#TIB
-TRAILING
TYPE
UM*
UM/MOD
UPDATE
USE
WORD

My brain melted

Bump because of update. This FORTH supports 100% pen, noteblocks, drums, and some other Scratch-specific features.

I have made some new videos about this FORTH programming language and a FORTH playlist:

1. (old) https://youtu.be/VZfUFnioLko 1 min <– Dec 26 2016
2. (new) https://youtu.be/FwEgRetggFg 1 min <– Feb 4 2017
3. (new) https://youtu.be/tPk1nNgq6NE 1 min
4. (new) https://youtu.be/tZOYPTv77pI 1 min
5. (new) https://youtu.be/nr0c87lrC64 1 min

https://www.youtube.com/playlist?list=PLD8D8534DD63B28EA

There is also a version for Scratch 3 that uses features unique to Scratch 3, but the Scratch 2 version also works in Scratch 3:
https://scratch.mit.edu/projects/302444111/

Extra features in the Scratch 3 version of #MOBLuSE_FORTH:

• Easier to type special characters on the command line.