So is Scandroid also Klayton? because on the Celldweller song Breakout it said (Feat. Scandroid)? I'll have to check that out.. Had no idea he had instrumental albums too, that could be pretty cool. Is Circle of Dust also just Klayton or another band? because again it said on Jericho (Circle of dust)? That's confusing
Scandroid was two people to start with but the second left years before the album was recorded/released. They have credits on two of the songs, but it's basically 99% Klayton, I can't even hear the influence from another person in those songs at all. There's a cover of Shout on the album aswell, obviously not written by him.
Circle of Dust was Klayton's band during the 90's before he started Celldweller, but he revived the project last year on his own. The old albums are more collaborative (though he was the main driving force), but the new one is 100% Klayton.
Regarding featuring his projects with one another, I think it's just to link them all together of sorts and to have references to his other projects in each. He's essentially just featuring himself.