When I lived in Golden we always used the light rail. Not sure where you could get on in Littleton. It’s easy enough to find out though.

A lot of the light rail stations have decent sized and pretty well lit parking lots. You could just drive to the station and hop on the train.

I haven't lived there in a while - back in the day I for sure would take the Light Rail places.   Now, I'm completely unsure if its still safe.  Colorado went from the 16th most dangerous state in the US to the 3rd.

Yes, light rail is what you seek. It's an 8-minute walk to the stadium from light rail. The train can fill up after shows.

It will be a little bit "rowdy" but it's just drunk people.

From Littleton you can take the "D Line" to the "Empower Field" station. You may have to transfer, I am not sure.

This might help

Like the man said, at your end you could board at either the big station at Santa Fe and Mineral or the one right next to ACC.

At the north end, the Auraria West and Invesco Field(l (I don't think they've changed the name) stations are both within a few minutes' walk.

Depending on how big the event is, RTD security may be checking tickets on every single person getting off a train at Invesco and writing up people who don't have them. I'd go through Auraria West just to avoid that entirely.

Alternately, the Route 31 bus lets off on the other side of the stadium. Its south end is somewhere in Littleton. Slower but might be less crowded.

ETA: the parking lot at Mineral is huge and Littleton PD at least used to hammer it pretty heavily.