Unfortunately there is no demo version. I put the game behind a paywall to ensure only the people that know about or have followed the project would be interested in buying it.
Apologies for my late reply. It seems 7Zip or WinRAR will automatically extract both files if you extract from the first file. I have updated the installation instructions to help future travellers.
Linux release won't be in the pipelines anytime soon unfortunately. I'd like to focus my efforts to first getting the game out of alpha state before porting to other platforms.
