With lists of items it is often a given that they are abbreviated. Sometimes they will follow a leading sentence, for example:
In my spare time I go:
You could take any one of the activities from the list and tag it on the end of the leading sentence, remove the colon, and you'd have a grammatical sentence.
With statistics, this can be even less verbose, as you are into the realm of mathematics. Consider:
2 + 2 = 4
There's no need to make this any more verbose and say "the sum of two plus two is four". The numbers speak for themselves.
Likewise with your game stats. Saying "creatures killed: 4" is in effect saying "the number of creatures you have killed is four". Statistics often need no introduction, especially if they are on a page titled 'statistics'. You recognise these as statistics in your game so there is no ambiguity about what they are. It is a given that what you will read is the number of times various metrics have been counted.
You said that "click" and "birth" (as in "cookie clicks" and "total rebirths") are not verbs. Actually, they can be - to click on something, especially in a computing sense, is an action and a verb. Likewise, 'birth' can be used as a verb to mean the act of giving birth, or sometimes assisting with one. Both have an '-ing' form - clicking and birthing. However, you can count the number of times an action took place and in doing so it acts as a noun. So, "he clicked 5 times" could be counted as "5 clicks".