just to clear some things up here
First game to come for amiga (commercial) was MINDWALKER and it was bundled with all a1000's V1.0 machines (with 256kb mem)
and you needed the boot disk too.
as for the guys mentioning defender of the crown, well DOTC was an C64/MAC/PC port from 1983 and ported to amiga in later 1985 and redone to the max.
EA's game One-on One is a close number 2 for the first games to appear on amiga.
public domain ? well that have to be "that gun game" , based on a coinop..damn i cant remeber it but its from 1987 afaik and it had only 3 doors and 2 diffrent types of people to shoot, innocent (woman) and enemy (man with gun) .. was the name ShootOut? cant remeber...
anyway....good luck on finding the answers..
check HOL.ABIME.NET for more info.