It's important to note that TimeSplitters Rewind has been in the work since almost 8 years.
It is handled by a group of fans who were given permission from Crytek back then.

The right to the IP have since been bought by THQ but, and surprinsingly so, the project remains active.
That's also despite the facts that THQ have its own plans for the future of TimeSplitters. 

From 2012 to 2018 nothing really interesting have come out of the works on TS Rewinds.
The project really started to gain traction in early 2019. Fast forward to now, the team is now 57 strong and the project progress is substantial.
The last progress update video was truly impressive and the content is very loyal to the original trilogy.
Honestly, I had lost all hope in this project years ago, but now I'm starting to get excited again.

There are indication that works are in progress at THQ for a new entry (don't know if it is a remaster or sequel).

For Rewind though, seams to me that the project as enough traction now that the only thing that would prevent the game from being finished is THQ pulling the trigger.

So this a remaster? Has my money if anything comes out.

It's supposed to be 100% free.

Just so you know the dev's of TS Rewind have a discord and no i won't link due to reasons.