TCO18 Marathon Round 1 RoadsAndJunctions started on May 9th and will run for a week. You can find it in the list of active contests. I am the writer :-)
This year the online part of the Marathon competition consists of 4 main rounds, each running for a week. The winner of each main round advances to the finals, and so do 8 participants who accumulated the most points across all main and lightning rounds. 150 competitors who accumulate the most points get t-shirts; given that each round awards points to top 50 places, it's quite possible that the t-shirt condition will transform into "top 50 in each round get t-shirts".