The idea of the spin mechanic in Milpa originates from an old computer game called Reverse published in the book BASIC Computer Games in 1978. In Reverse, the player is presented with the digits 1 through 9 in a random order. The object of the game is to created a sorted list by reversing the order of any number of the digits, starting from the left. There is no time limit, and there is no way to lose - the player either achieves the goal or stops playing.

I enjoyed the game a lot when I was younger, and even programmed it into a TI-85 so I could share it when friends at school. However, I noticed there are two issues with the game: for many people, the “reverse” mechanic is difficult to visualize (it needed animation) and sorting numbers just isn’t that fun.

Recently I wanted to do something fun with the game idea, and eventually settled on turning it into a match-3 game with a “spin” animation. After messing around with different parameters, the game settled with four tile types and nine tiles to spin. This felt pretty fun and also prevented the situation of being stuck with no possible matches.

Adding an arbitrary time limit to the game doesn’t appeal to me. When I see timers in games I think, why do I only have so much time? Who decided this? Would Tetris have been fun if each piece had a time limit in which it could be placed instead of falling by gravity? So, to make the game challenging, the player is given a goal of collecting a minimum number of tiles and an enemy that can eat tiles before the player has a chance to collect them. The enemy (a skull in the final game) moves faster and faster as the player progresses, and the goal gets more difficult. So, instead of trying to beat a timer, players race the antagonist. (The object of not creating an arbitrary timer was still in vain though - many players still associate the enemy with time).

At that point, the tiles were simply different colored discs, and the game needed a theme. The tiles should be something the player intrinsically wants to collect, like jewels or candy. At the time I was reading 1491: New Revelations of the Americas Before Columbus by Charles C. Mann and the concept of a milpa - a field of maize and other crops - fascinated me. Consider this quote from Mann:

Milpa crops are nutritionally and environmentally complementary. Maize lacks the amino acids lysine and tryptophan, which the body needs to make proteins and niacin;…. Beans have both lysine and tryptophan…. Squashes, for their part, provide an array of vitamins; avocados, fats. The milpa, in the estimation of H. Garrison Wilkes, a maize researcher at the University of Masachusetts in Boston, “is one of the most successful human inventions ever created.”

The goal of the game became collecting crops for the player’s Mesoamerican empire.

Finally, the game design and the graphic theme went through tweak upon tweak upon tweak to get it just right in terms of difficulty, fun factor, and appearance. Testing early versions of the game on friends and family proved to be invaluable. A powerup was added, and a fifth tile type was added to advanced levels. It is still not perfect - some find the game too hard, others too easy, and there is plenty of room for visual polish - but I think there is a good balance and Milpa became a fun, unique game.

P.S. For the curious, so far my best score is 32,350 in Year 19

This entry was posted on Monday, April 16th, 2007 at 5:54 pm and is filed under Game Design. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.