Sony Computer Entertainment Europe (yes, the company is retaining its old name in the Old Continent, at least for a while), recently trademarked "The Sentinel" in the European Union, sas you can see below.

At the moment we don't know what the trademark could be for, but the classification indicates games (9) and games with online elements (41).

We'll have to stand by and see what this will be about. E3 is coming, after all.