Time Anomalies

I had a blast of nostalgia from playing Turok and really love the idea of Native Americans running around a planet pieced together by an assortment of time periods fighting dinosaurs and aliens, I've always wanted to try a universe like this.

I was thinking having multiple factions, a Modernized Roman Empire, Native American Tribes, and Alien Race two, and all sorts of wildlife from all time periods. Of course there will be chaotic time rifts, evil technology, magic, and a big bad guy. Does anyone have anything they'd like to see or any other concepts.

Here's a sort of WWII-era Legionary:

That's something along the lines of what I was thinking, I just pictured the alternate Romans more colorful and clean looking.

And they'll have dinosaur war mounts.