Watt-Wise Game Jam


Build delightful games that use as little energy per second as possible in order to make games and computing more sustainable, and to discover new directions for software aesthetics.

2024 Results

power graph showing all entries' power consumption during evaluation

In 2024, WWGJ had three awesome entries:

Here’s how their scores came out:

Tile Garden - #1 “From Scratch” Game

Tile Garden banner image

Overall Score: 31 points (rounded)

power graph showing Tile Garden's power consumption during evaluation


Consuming a tiny 2.83 Watts, playing Tile Garden for an hour uses the same amount of energy as running an LED light for 3 hours. This game is a charming pixel-art plant-building game. Completing plant structures earns you income for every leaf attached to the structure, which in turn allow you to buy more tiles to build plants from. Over time you unlock new tiles to build ever-more-complex structures. It can take a while to figure out exactly what you’re doing due to the lack of in-game help (and you might, like one judge, never realize you can move tiles you’ve previously placed), but the experience is fun and the structures you can build intricate.

Green RPG - #2 “From Scratch” Game

Green RPG banner image

Overall Score: 30 points (rounded)

power graph showing Green RPG's power consumption during evaluation


Green RPG is, in the author’s own words, “more of a tech demo than a complete game.” However, it manages to implement a JavaScript raycaster world with pixel graphics and wall collision detection while using a measly 0.83 Watts. This is equivalent to the power required for an efficient nightlight. There isn’t much to do within the game world beyond walk around the simple level and admire the pixels, but certainly no energy is wasted here.

Heat.WAV - #1 “Optimized” Game

Heat.WAV banner image

Overall Score: 26 points (rounded)

power graph showing Heat.WAV's power consumption during evaluation


Heat.WAV is a wonderful satire about your life as a demon contractor on a mission to make the surface of the Earth back into the Hell it was in prehistoric times. Playing this game for an hour uses the same amount of additional energy as running your ceiling fan for 4 hours (including the energy of the all of the fans you must sabotage in your demonic quest). The game is fully and professionally voice-acted, includes numerous puzzle levels, and has a memorable graphical style. You might encounter the occaisional bug, and the gameplay loop is sometimes a little slow, but it’s absolutely worth a playthrough.

How were games evaluated?

Three judges played each game on three different computers. The computers were all running Ubuntu 23.10 from a bootable USB, all disconnected from the internet, and all had their CPUs locked to 2GHz. The cable connecting the computers to the wall was instrumented with harmon-e to gather high-resolution measurements of the apparent power flowing up the cable. The raw data from harmon-e was collected and analyzed in watt-wiser, and the game’s energetic impact was determined by subtracting the average power draw of the idle system from the average power draw while running the game.

The judges also rated games against our rubric to provide a qualitative metric for the experience of playing the game. We intended to factor in ratings from the community as well, but Itch.io is glitching such that we’re unable to access community ratings.

For the extremely curious, the raw data (228MB compressed, 714MB unpacked) from the judges’ energy measurements is available. Unzip it and open the benchmarks.json file in watt-wiser’s “Benchmark” tab via the “Load from File” button. It may take a while to load all of the data (it’s quite large).

The hardware of the judges has a significant impact on the energy characteristics of their gameplay. Here are the CPU and GPU of each judge’s test computer:



Watt-Wise is a challenge to build low-energy games. Entries will be judged both for the quality of their gameplay experience and for the average energy consumed per second of gameplay (using a hardware monitor between the computer and the power outlet).


Computers and video games have an enormous carbon footprint 1 2 3. We can minimize the carbon footprint of running games on non-renewable power grids by using less power, but this is actually the lesser goal.

By focusing our jam on low energy use, we also target the ability for older hardware to run it. How? Well, the physics definition of “energy” is the “capacity to do work”. If program X uses more energy on my computer than program Y, it’s because it actually does more computation. There are differences in the efficiencies of certain tasks enabled by hardware, of course. GPUs make lots of 2D and 3D math vastly more efficient that pure-CPU approaches. However, we can compare two programs on the same hardware (while holding factors like clock speeds constant) to compare how much energy is required for them to function. The program using less energy does less work on that hardware, and is likelier to run better on even older hardware.

The end goal isn’t just to build some great games, but to discover which techniques of game and software design are both beautiful and efficient, and to apply those lessons to software beyond video games.


We are developing both hardware and software estimation techniques for measuring energy consumption. Participants can use our open source power estimation tooling while developing their games to optimize for using less power. When it’s time to judge games, the community will rank their favorite games, and then the judges will play those games and measure their hardware consumption using a more precise hardware monitor. The games that strike the best balance between fun gameplay and low energy consumption win!

You can find an explanation of the scoring rubric used to evaluate games here.


How do I join?

Join one of our online communities to get the latest news, discuss game ideas, find collaborators, and more. Join us on Itch.io and Discord or IRC to get involved.

Is there a theme?

The theme is not a factor in determining the score of entries, but we do have one. In 2024, our theme is “Breaking and Re-Making.” Whether that’s relationships, objects, ecologies, worlds, bones, or anything else is up to you.

Can teams participate, or only solo game developers?

Teams are welcome!

Can I submit an existing game, or does it need to be a new one?

We will accept two categories of submission:

We’ll evaluate the two categories separately and recognize excellence within each category. That way optimized games are only compared against other optimized games, and new games are only compared against other new games.

What restrictions are there for submissions?

Games must:

How do I make a game energy-efficient?

The simple answer is “make your game do less work,” but there are many ways to go about that. Let’s think about what your game does as it runs:

If we call your tick rate tps and your frame rate fps, and we call the cost of one tick and one frame Ct and Cf respectively, we can model your energy cost per second as:

tps * Ct + fps * Cf.

The most obvious wins come from decreasing tps and/or fps, since they are static multipliers on the cost of running your game every second.

TPS and FPS Optimizations

In your game, you may be able to update some sub-states of your game world (physics, AI, networking, etc…) far less often than others. This lets you save work per-tick. There’s a delicate balance here, espcially for physics-based games, but doing fewer game ticks saves energy.

For FPS, a number of optimizations are available:

Cost of Tick Optimizations

However, there’s a limit to how much you can decrease these while keeping your game feeling pleasant and interactive. Instead, let’s focus on optimizing Ct and Cf.

Ct is the cost of updating the state of your game. Depending on what kind of game you are building, there are many different things you could be doing. However, the best way to decrease this cost factor is always the same: make thoughtful choices about how much of work your game needs to do in order to be fun. If your game keeps track of physical objects, carefull consider how many of them you really need and how realistic their physical behavior needs to be.

Also, stop updating your world state when the player can’t see it anyway, like when they’re looking at a menu.

Cost of Frame Optimizations

Cf is the cost of drawing one frame. Here, we can consider many ways of doing less work that are relevant for many games:

Some games may be able to combine many of these optimizations to great effect.

TODO: there’s a lot more to say here. Check back later.