informative pixels here: https://github.com/dell-oss/Doradus/wiki/Architecture%20(Spi...

What advantages does this have over Titan?

Giving a quick look, "graph" here seems used more like a "relational nosql" than an engine to do perform complex/custom graph traversal or implement algorithms.

Does anybody know of something similar for time-series based models?

The Cloud Monitoring team at Rackspace developed a time-series database on top of Cassandra called BlueFlood DB. You can find information here: http://blueflood.io/