Just wondering how you unlock the Eat Cake achievement in Game Dev Tycoon. The achievement says "Show them red barrels some action."
Later on in the game (at around year 20 or 25 or so), Dave Johnson will offer you the ability to put some red explosive barrels in your game. You need to accept this offer and then put the barrels in to a particular type of game. During the development of every game up until you use the option, you will gain a new option to include the barrels in the game you're currently developing.
The barrels need to go into a good, well received game, of a genre where the barrels are appropriate (so don't go sticking them into a medieval game, for example). You'll want to include them in a military, space simulation or a science fiction game.
Once the game has been released and well received, Dave will offer you cake. Accept the cake to get this achievement.