First step, create the universe...
Seriously, even if you could write a clone of Photoshop why would you release it only for the Amiga? The APIs are primitive in Amiga OS 4 compared to OS X, Windows or Linux so it would be even harder than writing for them. And then it wouldn't be a killer app, people could still use Photoshop on a modern OS.
Let's face it, there are no probably killer apps in 2009, and certainly none that would convince people to plunk down €1000 on a computer than is roughly as powerful as an iPhone.
Look at what people do with their computers:
1) Write letters and share documents, there's a rudimentary word processor that won't open current MS Word Documents.
2) Sync their phone/iphone - MP3s, contacts, calendar, etc. No can do. Forgot my cable, guess I'll use blue tooth - forget about it...
3) Edit pictures - 12 MP raw? Remove red eye?
4) Make a video for youtube, edit video. Nothing on OS 4, video toaster, slow & primitive on old hardware. Doesn't handle modern digital input well.
5) Surf the web, sort of, in a half arsed way, yes.
6) Email, possible, if you happen to like the one program available (YAM).
7) That printer you bought in this century, wouldn't it be nice to use it's features?
That autofill pdf
Just a few things to start. There's more, an OS that doesn't remember where you put icons, that doesn't have a decent search facility, that doesn't have memory protection.
A decent, modern IDE would help, but even then the programmers aren't there.
