MECH WEEK: Heat

Exploring heat build-up and resource management in mech games

Welcome to Skeleton Code Machine, a weekly publication that explores tabletop game mechanisms. Spark your creativity as a game designer or enthusiast, and think differently about how games work. Check out Dungeon Dice and 8 Kinds of Fun to get started!

This is part of Skeleton Code Machine MECH WEEK — a week of articles (and coloring contest) about mechs in tabletop games: Part 1 - Is Iron Man a Mech?, Part 2 - Heat, Part 3 - Combat, Part 4 - Pilots, Part 5 - Systems.

Welcome back to MECH WEEK!

Yesterday we explored the idea of mechs, and what features are common to mechs. Are they just featherless bipeds with autocannons? Or is there something more to it?

Today we look at a venerable mech game that is four decades old and yet still going strong.¹

BattleTech

BattleTech: A Game of Armored Combat

BattleTech is one of the most famous tabletop mech combat games and acts as a blueprint for many of the games that have followed. Wikipedia rightfully calls it a “wargaming and military science fiction franchise” because of it’s sprawling history and the many forms it has taken: board games, role playing games, collectible card game, novels, and the infamous BattleTech: The Animated Series.²

While I’m no expert, I have played BattleTech: A Game of Armored Combat (Arrastia, Bills, et al., 2019) a number of times (throwing fistfuls of d6s) and enjoyed the BattleTech (2018) video game. There are so many features that are worth exploring: line of sight, modular mechs, worldbuilding, and more.

For MECH WEEK this year, however, I’d like to focus on heat.

Heat build-up

BattleTech popularized the concept of heat as a critical resource, which has become a hallmark of the genre:

Heat build-up is a BattleMech’s greatest limiting factor. Though a ‘Mech dissipates heat through its heat sinks, heat builds up when it moves or fires its weapons, and a high rate of activity can produce more heat than a ‘Mech can dissipate. A warrior who pushes their ‘Mech past its limits eventually must pay the price.³

Each mech system (e.g. weapons) generates heat that must be dissipated via heat sinks. Walking generates 1 heat point. Running generates 2 heat points. Firing an Autocannon/20 generates 7 heat points.

It’s not just internal sources that can generate heat. External sources like engine critical hits (+5/+10 heat per turn), ground fires, and heat-based weapons (e.g. flamethrowers) all add heat to a mech.

Fail to control the ever increasing heat and you risk systems shutting down. Pilots start to take additional damage if the heat is too high for too long, being literally cooked inside their cockpits.

In BattleTech, heat starts at 0 and goes up to 30. At zero to 13, you might see some negative impacts to movement or firing, but you’ll generally be OK. Starting at 14+ you run the risk of your entire mech shutting down. At 19+ your ammo supply might explode.

To dissipate heat, your mech needs a heat sink. Single and double heat sinks dissipate 1 or 2 heat per turn, respectively.⁴ Walking through snow or a quick dip in some water will also reduce heat build-up.

The addition of heat to BattleTech takes a tactical combat game and makes resource management a core mechanism.

Heat as a resource

As a game mechanism, heat is essentially a resource to be spent, much like resources in any other tabletop game. The key difference is that it is tracked as the inverse of how much you have left to spend. High numbers are bad and low numbers are good.

It is really your “heat capacity” (i.e. how much more heat you can tolerate) that is the resource.⁵ If your mech shuts down at 30 heat, that means you have 30 units of heat to spend on actions and attacks. This could have just as easily been modeled where high numbers are bad and low numbers are good.

Either way, the question becomes when and how to spend that heat capacity. The skill a mech pilot (player) brings to the table is knowing when to spend some heat: make a shot with good odds of hitting or flee to avoid getting killed. It might also be worth having your mech shut down on overheat if it ultimately wins you the game.

Resource-based combat can be an interesting way to approach combat in games, and not just in mech games. Resource management was a topic in the interview with Spencer Campbell about REAP.

Rondel heat management

Auctoratus by M. Allen Hall

We explored rondels when we looked at Grasping Nettles earlier this year. A rondel is an action selection mechanism where actions are represented as “pie wedges” in a circle. The player uses a token to move around this circle and take actions.

Auctoratus by

M. Allen Hall

uses a rondel as an interesting mech heat management system. Each player’s mech has a rondel with six wedges and a central circle. Cubes are places on the components to track both weapon “charges” and heat:

• Distribute: After a component is used, the cubes on it are distributed clockwise around the rondel. One cube is placed on each wedge.

• Discard excess: If cubes are distributed all the way back to the starting wedge (i.e. 6+ cubes), the excess cubes are placed in the center Heat Sink circle. This reduces cubes available for charges in future turns.

• Vent: Cubes are regained when a player takes the “Vent Heat” action, pulling any cubes from the center Heat Sink and redistributing them around the rondel.

This system tightly couples both action and heat mechanisms. More charges (cubes) on a component allow more powerful actions, but also create more heat to be dissipated… some of which will end up on the heat sink. Weaker actions have less heat, and can be used more often without risking (temporary) loss of cubes.

MECH WEEK Coloring Contest

Plato’s Mech entry by Nick Gralewicz (Deep Dark Games)

Don’t miss your chance to win a copy of Make Your Own One-Page Roleplaying Game (PDF) by entering the Skeleton Code Machine MECH WEEK coloring contest! Download Plato’s Mech at either the Exeunt Press Shop or itch.io.

Conclusion

BattleTech CPLT-C1 “Catapult” with 2x LRM-15

Some things to think about:

• BattleTech is 40 years old: Created in 1984 by FASA Corporation, BattleTech has had unbelievable influence on the very notion of giant, combat-focused, mechs. If you are planning on making a mech combat game, I strongly suggest you become at least a little bit familiar with BattleTech.

• Heat: Heat and overheating is a familiar trope in games. Used poorly, it’s a mechanical way to restrict players from doing things (e.g. unlimited ammo guns overheat). Used wisely, however, it can be a resource that creates interesting decisions and challenges for players in a thematic way.

• Mix mechanisms: Auctoratus is an example of taking a well-worn mechanism like heat build-up and combining it with other mechanisms to make it more interesting: heat from BattleTech mixed with a rondel/mancala mechanism similar to Crusaders: Thy Will Be Done (Jaffee, 2018).

What do you think about heat in mech games? It is so common that it has almost become an expected mechanism.

— E.P. 💀

P.S. This is Part 2 of MECH WEEK. Don’t miss Part 1 - Behold, Plato’s Mech. Subscribe to Skeleton Code Machine so you don’t miss any of the action this week.

---

Skeleton Code Machine is a production of Exeunt Press. All previous posts are in the Archive on the web. If you want to see what else is happening at Exeunt Press, check out the Exeunt Omnes newsletter.

1. I’m always pleasantly surprised to see so much BattleTech on the shelves at Barnes & Noble.

2. Secret Galaxy did an episode on the BattleTech cartoon: The Wild History of Battletech: The Animated Series - Yes, It's Real

3. Excerpt from the BattleTech: A Game of Armored Combat rulebook.

4. Heat sinks aren’t the only method. The BattleTech Manual also lists partial wings and coolant pods and possible ways to reduce heat build-up.

5. I do not mean heat capacity in the thermodynamic (Joule/Kelvin) sense of the world. If I did, the specific heat capacity (c) of a mech would probably be the same as steel which is about 0.460 - 0.502 J/g-°C.