Players
2 players
Time
10–15 minutes
Objective
Win the most cards by playing lower carbon emission activities than your opponents.
Deck
- A single deck of Activity Cards
- Each card includes:
- Activity (e.g., Driving, Flying, Biking, Solar Power)
- A carbon score (number value)
Setup
- Shuffle the deck
- Deal all cards evenly to players (face-down)
- Players do not look at their cards
- Keep cards in a stack in front of you
Gameplay
1. Flip
All players flip their top card at the same time
2. Compare
- The card with the LOWEST carbon score wins
- (Reverse of traditional War)
3. Collect
- Winner takes all played cards
- Place them at the bottom of your stack
Carbon Clash (Tie Rule)
If two or more players tie:
- Each tied player places 1 card face-down
- Then flips 1 card face-up
- Compare again → lowest carbon wins all cards
Learning Twist
Before taking the cards, each tied player must say one way to reduce emissions related to their activity
- If they give a valid answer → continue
- If they can’t → they lose 1 extra card to the winner
End of Game
Choose one:
- Play until one player has all the cards
OR - Set a timer → player with the most cards wins
Key Rules to Remember
- Lower carbon = better
- Always flip at the same time
- Only use the card deck—no board, tokens, or extras
Key Cards
| Activity | Carbon Score |
| Walking | 0 |
| Biking | 0 |
| Solar Power | 5 |
| Wind Energy | 5 |
| Public Bus | 40 |
| Train | 45 |
This is a really clean and well-structured rule set. You’ve nailed a “reverse War” mechanic and made it immediately understandable, which is harder than it looks. The LOWEST score wins twist is doing a lot of heavy lifting, and it works because your carbon values are intuitive and consistent across activities. The, “learning twist,” is honestly the standout! it forces players to actively think about sustainability instead of just passively playing, which is exactly what a serious game should be doing. My only push: right now, the game is almost too clean. There’s very little decision-making, so after a few rounds it risks feeling like luck-of-the-draw. You might consider adding a light strategic layer (like letting players hold 1 card in hand or choose between two draws) to give players a sense of agency without overcomplicating it.