"Erik" was my first foray into the world of making 16-bit games. It was a vertically scrolling platformer, drawing inspiration from a number of contemporary games. I originally created it on the Atari ST, and then scraped enough money together to buy an Amiga, and port it to that. There were no additional features on the Amiga version, and no enhancements over the Atari ST version. It was again published by Atlantis Software, but after they went bust, I released it as Licenceware.
The ST wasn't very fond of scrolling sideways, so I designed Erik to be vertically scrolling only.
The Acorn Electron wasn't fond of scrolling at all, so this was new and exciting ...
The sounds were very low quality samples (since the Atari ST hardware wasn't very good with sound) and sound horrific.
The Amiga version was a pretty straightforward port. The sprite code had to be re-written for the different screen memory layout, as did input and audio handling. I don't think I used any extra features of the Amiga much, but the audio was much easier, and I used the blitter chip for the screen scrolling.