This mod for Sethbling's SMW Jailbreak is basically Dotsarecool's "SMW: Silhouette Blends Edition" but can technically be played on a real cartridge! The silhouette effect turns the game into two colors: the foreground which is black and the background which is another solid color. Here is a few screenshots if you don't get what I mean: http://imgur.com/a/qZGZq

Some issues that persist is that the effect breaks on the overworld sometimes. It also breaks in Mode 7 boss levels and also during HDMA windowing effects when it becomes really flashy (epilepsy warning).

Compiled code:

A9 40 85 44 C2 20 AD 01 07 C9 00 00 F0 03 E2 20

6B A9 FF FF 8D 01 07 E2 20 6B

Raw Code:

LDA #$40

STA $44

REP #%00100000

LDA $0701

CMP #$0000 ;checks to see if the background is black

BEQ .fix

SEP #%00100000

RTL

.fix:

LDA #$FFFF

STA $0701 ; sets it to white so you can see stuff

SEP #%00100000