This is the full download for Xenonauts: Community Edition. The archive is available in zip or 7z format - they have the same contents, you only need one.
Steam users shouldn't download this - instead, if you use Steam, switch to X:CE from your Steam Library. Right-click Xenonauts, choose Properties, and then in the Betas tab, pick "community" (no access code/password needed).
For installation instructions and changelog, see: X:CE 0.35 release announcement