Provably fair
Every round's outcome is committed before you bet and can be checked after it closes.
The method
Before every round the server picks a secret seed and publishes only its SHA-256 hash. You pick your own client seed. The outcome is computed from both seeds together.
After the round the server seed is revealed. You recompute the outcome with the same seeds and check that it matches. Because the hash was published before betting, the result could not have been changed.
Per-game keys
Each game runs on a daily cryptographic key. The system compares the expected house result with the actual one and halts itself if they differ beyond a small tolerance.