It appears to be run by https://tacticalar.net/ based on the email in the event.
Based on the videos they are using a normal VR headset and attaching controllers/sensors to prop guns (or real guns in some cases), and then you play through a shooting range game which presumably keeps score etc.
If I click "buy software" on the page it takes me to this Steam (video game purchasing platform) page https://store.steampowered.com/app/720510/Tactical_AR/
In all of the videos there, they seem to be shooting normal range targets or "floating red circle" graphics. Not aliens or moving enemies etc.
I would assume you are essentially getting to play it for an hour (I damn sure hope so for $30) and your high score will be noted.
This is not an unreasonable price for playing with VR for a while generally. There's a chance you won't like VR itself (if this is your first time) and might get motion sickness or something. If you're mostly standing there shooting things though it should be fine.