The following is an excerpt from the Designer Notes for Offworld Trading Company. The game, an economic RTS set on Mars, releases on April 28, 2016, and is available for purchase here.

One of the trickiest parts of the design was how to handle when the player needed to consume a resource but had none in her stockpile. Our initial solution was that every time a player could not supply the needed Power, Fuel, or life support, the game would lower that player’s stock price. If this penalty was applied too many times, the company would drop to a price of $1 and would soon be acquired by a competitor. The system worked, in that players would be afraid to run out of required resources, but the system was also obtuse and caused permanent damage to players; each stock penalty lasted for the rest of the game, which meant we were encouraging a very conservative strategy of always making required resources first.

The solution was the debt system, which kept track of each time the player needed to buy a required resource from the market, acting as an unlimited line-of-credit. The debt would also affect the player’s stock price but, significantly, a player could pay off the debt to recover later in the game. Too much of a resource shortfall early in the game was no longer a death sentence. The system now worked because it was transparent, players could see how bad their debt was getting and decide when to fix the problem.

However, as all game designers know, give players a new feature, and they will do everything they can to break it to their advantage. “Debt diving” became a term among the players for ignoring debt in favor of resources that produced straight cash in the hopes of buying out the other players before dying to too much debt. It was a dangerous strategy but, in the hands of the best players, also a dominant strategy. (Simply put, a player with $300K in cash and $200K in debt can easily beat a player with $100K in cash and no debt, even though their net assets are identical.)

The solution was bond ratings, which changed the interest rate paid on debt each day depending on the ratio of a player’s debt to his total assets. The better bond ratings (AAA, AA, A) had interest rates between 2% and 6%, which were quite manageable. However, once a player sunk to a D rating, the interest rate jumped to 30%, which meant that a player could die to debt as her debt might increase faster than she could pay it down. Finally, players with a D rating were also locked out of the black market, which meant they could no longer sabotage their competitors and were also vulnerable to sabotage without access to the defensive Good Squad. Basically, D debt is very bad — bad enough that while players would still use debt as a tool to accelerate their progress at times, they were also acutely aware that going too far could mean disaster.