The Amiga version of Encounter was first released in 1991 (a full seven years after the original release) by Novagen Software.
The classic Encounter gameplay has been retained perfectly and the graphics have been updated nicely. Your tank zips around quickly and bullets come at you even faster. Everything you’d expect from a conversion to 16-bit.
Of the two 16-bit releases, the Amiga version has a slightly wider display compared to the ST version. Otherwise they are pretty much indistinguishable.
More: Encounter on Wikipedia