In my personal view, the lack of a playable Alien campaign was what majorly hurt the sales. Casual gamers generally don't want to feel constantly victimised. They want an empowerment escapism fantasy after the frustrations of their day. It's a formula which might work for something with a much smaller budget, but they needed something more for a product with relatively high development costs. The people who do want to shell out for that are just not going to be enough.
Yes, 'Colonial Marines' initially had high sales, but a lot of people who bought it were still doing so for what they assumed to be an empowerment fantasy with squad mates vanquishing the enemy and saving the day amidst loud explosions.
For a film, it's different. A similar presentation style and sense of atmosphere would work very well for that.
'Covenant' did come close during the initial backburster scene, but as that was bizarrely released to the public ahead of release, nobody was going to purchase tickets for the one scene which they could already watch for free at home.