Gates of Zendocon is a side-scrolling shooter very similar to the original arcade shooter of this type, Scramble. Unlike Scramble, however, there are 51 game areas in total, but the player fights through a subset of them through branches, choosing the next area to visit.
Some aliens will join you when shot (power-ups). Alien bases in each area allow you to repair your weapons and shield, but landing at the wrong time will cause your ship to explode and lose all power-ups.
If you had this game on your Lynx and want to experience some nostalgia, absolutely buy this. If neither point applies to you, probably give it a pass. The Lynx and its games were groundbreaking at the time, but haven't aged particularly well. Especially Gates of Zendocon.
Look I'm as big of a fan of this game and the Atari Lynx as it gets but this is such a lazy "port" it's mind boggling how this was allowed to be released on Steam as it is.
All this is is the LibRetro port of Handy that is programmed to run alongside the ROM that's in a separate folder. And seeing the name of the ROM in the files is "Gates of Zendocon,...