Article 1021 of rec.games.corewar:
From: kv07@IASTATE.EDU (Warren Vonroeschlaub)
Newsgroups: rec.games.corewar
Subject: Impdwarf
Message-ID: <1992May29.090647@IASTATE.EDU>
Date: 29 May 92 14:06:47 GMT
Article-I.D.: IASTATE.1992May29.090647
Sender: news@news.iastate.edu (USENET News System)
Reply-To: kv07@IASTATE.EDU (Warren Vonroeschlaub)
Organization: Ministery of Silly Walks
Lines: 54

Impdwarf did not do too well on the x-hill (it crawled up to #15 at it's peak). 
The main problem being that if the copy fails the program ends up killing
itself.  I tried to adress this problem in 2.0, but other problems cropped up
keeping in off the hill altogether.  The code is ;redcode-x

;name ImpDwarf 1.0
;author Warren Kurt vonRoeschlaub
;strategy It's the Imp that acts like a Dwarf
;strategy Slightly more prolific than original
start   spl 1
source  spl 1
go      mov #(1+dest-source),source
cloop   mov <source,<dest
        mov <source,<dest
        spl (247+go+go-dest)
; kill all but one process and start bombing
die     mov <dest,die
bomb    mov dest,<dest
        djn bomb,dest
dest    dat #250+start,#250+start
        end start

  The biggest problem (other than the one mentioned above) is with the kill
line.  It must somehow decrement the  dest pointer and put an illegal
instruction at die in one cycle.  The predecrement works, unless the program was
just copied over another program.  This caused the die command to go haywire
instead (especially if it copies an imp bomb or SPL bomb).

A similar system was used by Hide 'n' Seek:

;redcode-x
;name Hide 'n' Seek
;author Warren Kurt vonRoeschlaub
;strategy Play hide and seek, you're it.
source  dat #0
start   mov #dest-source,source
cloop   mov @source,<dest
        djn cloop,source
        spl (249+start+start-dest)
        mov hide,123
        jmp 122
hide    jmp hide
dest    dat #250+start,#250+start
        end start

  This actually made it onto the hill once (as #20).  It was rather suprising as
I had actually written it to check out the scanners (a B-field scanner will tie
it every time, except for an occasional loss).

***********************************************************************
* Warren Kurt   *  "I believe there is an inteligence to the universe *
* vonRoeschlaub *   with the possible exception of certain parts of   *
* kv07@iastate  *   New Jersey" -Woody Allen                          *
***********************************************************************