Why give the game a number? Just call it after the new protaganist, while creating another game that lays a lot of groundwork for a whole new generation of gaming. (It's just VR gaming this time.)
HL Alyx was really groundbreaking for its time in the VR world. Few other games combined the user experience, VR immersion, and grapichs into a good game. Just like how HL2 was groundbreaking in the physics department.
However, there is now an unkillable super hero who has gone through immense pain because of your choice. I hope you can find whomever put him in chains in the first place, before he finds you.