18 lines (a simple puzzle for Talos Principle and Witness)[now with a hint]

Games: The Talos Principle + The Witness
Level: 3+
Region Restrictions: No
Time: Until 24th December
Hints: 1) all you need for solving this is to know the English alphabet
Puzzle:

C is the third letter of the alphabet.
The eleventh letter on this line is the H.
Letter A takes the ninth spot in here.
Do not look for any help on eighteenth line.
This is just as short as line fifteen is.
Try to read this quickly sixteen times.
I made more than ten puzzles for SG.
I hope for at least seventeen solves here.
This is solvable in under six days.
I created it in less than eight hours.
You can win at most two great games.
I wonder who works it out first of all.
Line seven isn’t shorter than this is.
Nor is four any bit longer than this.
Possibly fifth line brings insight.
Text here or line twelve has no import.
You adjust line fourteen if it is untrue.
Tough to say what is number thirteen for.