More tutorials: http://iwannacommunity.com/forum/index.php?topic=2610.0
I encourage you to follow along in GameMaker! You can also make your own tweaks to the stuff you make. Here's the starting project: https://www.dropbox.com/s/8mk6uqjw1re4s2v/tutorial%202%20start.gmx.zip?dl=0

Timestamps:
0:00 Overview
0:38 BG squares
4:35 BG squares randomness
7:42 Lines attack
12:49 Sin wobble
14:42 Spiral
19:07 Confetti
21:37 Code style
22:28 Outro