See the Player guide, which explains the objective, and how to control the game.
The Sentinel is an overview of the original gameplay and its history.
No plans for MacOS or Linux are planned. However, Zenith runs on the Wine emulator for Linux, albeit with a few problems viewing hints and energy count. Zenith uses OpenGL and OpenAL, so there is potential for re-writing for other operating systems, but this will not be considered until the game is mature.
Zenith uses a procedural algorithm to generate landscapes from a single number. Zenith uses different algorithms than the original Sentinel game, to generate a wider variety of landscapes.
I might, or might not, develop this further, as a web app. Zenith could do with a better campaign mode, where the progression more closely resembles The Sentinel. I'd create better sounds, and perhaps use textures and other graphics if they improve the experience. I've also designed some game variations.
Not in the foreseeable future. If I develop the web version, I might make an open source release.
Press F9 to view the console window, then type HELP for a list of commands, which cover various options like controls, graphics quality, game tweaks, and some cheats.
You can also put these commands into your own scripts, and into the UserPreferences.zsc file which is run when Zenith starts, and DefaultStartGame.zsc which is run at the start of every game. All scripts are held in the scripts folder, and can be edited in a simple text editor like Notepad.
The project might be resumed in future. Until then, I don't plan to release source code.