First of all, the release date has been changed from TBD to a certain period:
The demo on itch.io is outdated, and due to the forthcoming Steam release I will not bring it up to date anymore. A closed beta test is planned, provided that I can find some people for it.
And finally, to come to an end, here are the abovementioned impressions:
An oxygen cylinder used as rocket
A surfacing sub-warp-artillery