STEM
RiverForge
When it rains on a hillside, where does the water actually go? Not wherever it likes - it obeys one rule: roll to the lowest neighbour, over and over, until you reach a low spot and pool. Trace that and you can find every pond, see the ridge that splits the rain into two rivers, spot the square that floods first, and watch what a levee really does to the water downstream. Predict the flow, then drop your own raindrops on the valley map. Real, tiny, deterministic earth science - no internet. Ages 9-14.
▶ Play it nowBuilt for sittings of about 20 minutes on the screen. That is our design budget, not a measurement.
Meet your mentor
Every Spark & Anvil app has a friendly mentor character that demonstrates, asks, and patiently scaffolds learning.
Mentored by Delta
#2a7fa8 Characters who teach
Meet the cast
RiverForge's crew ARE the shape of a watershed - the cast IS the curriculum: each character IS one fact about how water moves. Divide is the ridge along the top, the line that sends rain on one side to one river and rain on the other to a different one. Slope is the rule every drop obeys: always take the lowest step down, never uphill. Channel is where many paths merge into one - the square that carries the most water and floods first. Basin is the low pond at the end of the journey, where all the water finally pools. Delta, the mentor, is the wise river-mouth who has seen where all water ends up, and reminds the crew that a levee doesn't remove water - it just moves where it collects. Nothing leaves the device.
Divide
The ridge along the top - the watershed divide, the line that sends rain on one side to one pond and rain on the other side to a different pond
Slope
The one rule every drop obeys: always roll to the lowest neighbouring square, step by step downhill, never uphill
Channel
Where many downhill paths merge into one - the square that carries the most water, and so the one that floods first in a storm
Basin
The low pond at the end of every journey - a square lower than all its neighbours, where the water has nowhere left to go and pools
Delta
The wise river-mouth who has seen where all water ends up, and reminds the crew that a levee doesn't remove water, it only moves where it collects
What's inside
Learning goal
When it rains on a hillside, where does the water actually go? Not wherever it likes - it obeys one rule: roll to the lowest neighbour, over and over, until you reach a low spot and pool. Trace that and you can find every pond, see the ridge that splits the rain into two rivers, spot the square that floods first, and watch what a levee really does to the water downstream. Predict the flow, then drop your own raindrops on the valley map. Real, tiny, deterministic earth science - no internet. Ages 9-14.
Mentored by Delta — no data leaves the device.
How RiverForge handles your kid's data
- ✅ All progress, settings, and AI-generated content stays on the device
- ✅ No analytics, no tracking, no third-party SDKs
- ✅ Free — no ads, no in-app purchases
- ✅ No personal information collected from children — in line with COPPA (updated by the 2026 FTC amendments)
- ✅ No chat with strangers — play-together rooms use a short code and preset emotes, never typed messages