I think it's intended to be a complete curriculum (but I could be wrong).
Last fall my district replaced Math Trailblazers with engageny and nothing else. The curriculum director told us that they'd saved roughly $100k by going with the NY state curriculum (which had not been written when they adopted it).
I mentioned in the comments thread that, a few years back, I went to a talk by David Steiner, who said that the state was going to write a complete math curriculum states would be free to use or not. He didn't say anything about writing a supplementary curriculum. The plan was to write a complete curriculum districts could use instead of a curriculum they'd purchased from a textbook company.
I think what they've posted is the result.
Here's the wording from the website:
In order to assist schools and districts with the implementation of the Common Core, NYSED has provided curricular modules and units in P-12 ELA and math that can be adopted or adapted for local purposes. Full years of curricular materials are currently available on EngageNY, for grades Kindergarten through 9th grade in Mathematics and Kindergarten through 8th grade in English Language Arts (ELA). NYSED is working with our partners to deliver high quality curricular materials for all remaining grades in both Mathematics and ELA. In Mathematics, full years of instruction will be available for all remaining grades this summer. In ELA, full years of instruction will be available in 9th and 10th grade this summer and 11th and 12th grade this fall.They've posted 105 lessons for Algebra 1.
Common Core Curriculum