Westworld type TV Show network HBO

This is a surprise: Despite heavy promotion and positive critical buzz, Westworld viewership slipped slightly for its 70-minute season 2 premiere Sunday night.

The sci-fi drama delivered 3.0 million total viewers across cable and digital platforms.

That’s down a tad from the show’s series debut in 2016 which had 3.3 million total viewers across cable and digital platforms — making it the best opener for a new HBO series since 2014’s True Detective premiere (if you compare only the initial 9 p.m. telecast, last night’s episode was actually up slightly from 2016, but it’s the total sum of viewing that’s key here). The drama’s first season finale then set another record with 3.6 million viewers (which, more than anything else, suggested season 2 would open even stronger than the first).

HBO has pulled out all the stops to push the show’s second season, including buying its first Super Bowl ad in decades and building an entire Westworld-inspired town in Texas populated with actors playing androids during the South by Southwest film festival.

There are a couple mitigating factors. One is that HBO only showed the premiere twice last night instead of three times back in 2016. Another is the show’s longer-than-usual hiatus — the show came back after 16 months off the air. And the Westworld ratings, even the overnights, could grow as the season continues as reviews from critics who have seen the first five episodes of the season have been quite positive.

HBO points out that Westworld received nearly 80 percent of its viewing after its premiere night, helping lift last season’s overall average to 13.2 million viewers — the biggest debut season of any series in HBO history.

And these numbers still make Westworld the network’s second biggest hit after its tentpole fantasy drama Game of Thrones, which launched its first season in 2011 with a mere 2.2 million overnight viewers and gradually built up over the years to rake in an incredible 16 million overnight viewers for its seventh season finale last year (and generates up to 23 million viewers per episode when all forms of viewing are counted, including DVR playback and repeats).

If you watched the premiere, read EW’s deep-dive Westworld recap explaining all those revelations and twists.