Whilst going through the tutorial, I didn't realise at all that you had to drag the mutation connectors (or whatever the terminology was) into the slots. I tried clicking a lot of times and in the end just clicked continue. Didn't actually realise until the second (or maybe third) time that they had to be dragged. Maybe a voiceover saying "drag into slot", or some visual indicator to show it needs to be dragged. Or even allow the player to select the DNA connector and click a slot to put it in?