I sure was paying good attention during history, today!!
(Okay, actually, I really was. It was a lesson on WWI naval warfare.)

Anyway. Have some Half-Life/Black Mesa doodles!

(... Snarks are the best.)

Edit:

Here, have another one.

... It's a little strange, really. The headcrab-possessed people are my least favorite enemies, but I like drawing them for some reason...