Enrichment items and happiness are operationable! Attach an item to an enclosure, and from there you'll notice that you can press the "Play" button. Each item will entertain up to 10 dinosaurs per use, if their happiness is below 100%. When played with, the dinosaurs have a chance of getting a stat boost - though just what kind depends on the type of item, of course. ;D
Happiness decreases at a daily rate of 10%, the same as hunger, and only starts negatively affecting dinosaurs if it sits at 0% and remains there. Unfortunately, depressed dinosaurs like that will start doing self-destructive things like plucking their own feathers or scales, and will start losing 10% health daily. Luckily, playing with an enrichment item boosts them straight back up to 100%!
I'll be bug smooshing tomorrow and adding in some more new page designs. Also, give a ton of love to the mods, who are currently working on some helpful descriptions for the upcoming item library!