Social gaming outfit Zynga saw its shares tumble nearly 16% on Friday – its biggest one-day drop in two-and-a-half-years – after the company turned in underwhelming Q4 and FY 2014 numbers.

Bookings, the sale of virtual good and credits, rose 4% to $182.4m in Q4, well below market expectations of $201m. Advertising revenue rose 139% to $58m but the company still booked a $45m net loss for the quarter.

For the year as a whole, revenue fell 21% to $690m. Game revenue fell 28% from 2013 while ad revenue grew 34% to $153m. Net loss for the year came to $226m, of which $129m was stock-based expense, $24m in restructuring expenses and a $7m income tax benefit.

Looking for a bright side, Zynga pointed out that average daily bookings per daily average user was up 31% in Q4. Trouble is, the number of daily average users fell 2m to 25m, monthly active users fell by 4m to 112m and monthly unique users fell 9m to 71m.

Zynga’s efforts to transition to a mobile-focused company appear to be paying off, as Q4 mobile bookings rose 14% sequentially and 120% year-on-year. Mobile now represents 60% of total bookings and the company has set a 2015 target of 75% mobile bookings.

Zynga’s core franchises – Farmville, Zynga Casino and Words With Friends – reported 35% year-on-year bookings growth. Zynga Casino saw Q4 bookings rise 8% from Q3 thanks to a 34% gain in the Slots category, which was driven by a 27% gain in Hit it Rich! Slots and the launch of Wizard of Oz slots titles in mid-November. But Zynga Poker saw Q4 bookings fall 7% from Q3.

HASTE MAKES WASTE FOR POKER, SPORTS PRODUCTS