House Edge

Plain-English statement of how Orobas makes money and what it costs you to play.

Last updated: May 30, 2026

The one-sentence version

We take a 4% commission (“rake”) on the winner's profit at the end of each game. We never touch the principal — your original wager — and we never take anything from the loser beyond their stake. If a game is voided or refunded, no rake is taken.

How that actually works

Every 1v1 game on Orobas escrows the same amount of USDC from each player into a per-game on-chain account on Solana. We'll call that amount the stake. So the total in escrow — the pot — is twice the stake.

When the game settles:

The winner's profit is the loser's stake — the amount the winner gained beyond their original wager.
We take 4% of that profit as rake. (4% is 400 basis points, orrake_bps = 400 in the on-chain program.)
The winner receives back their own stake plus 96% of the loser's stake.
The rake routes on-chain to an Orobas-controlled treasury.

Worked examples

$10 coinflip

Each player stakes $10. Pot = $20.
The on-chain VRF settles. One player wins.
Winner's profit = $10. Rake = 4% × $10 = $0.40.
Winner receives $10 (their stake) + $9.60 = $19.60.
Loser receives nothing.
Orobas receives $0.40.

$100 chess match

Each player stakes $100. Pot = $200.
The game decides a winner (checkmate, resignation, timeout, or operator attestation).
Winner's profit = $100. Rake = 4% × $100 = $4.
Winner receives $100 + $96 = $196.
Loser receives nothing.
Orobas receives $4.

$25 binary event

YES player stakes $25 on “Will X happen?”. NO player matched at $25. Pot = $50.
Event resolves YES (or NO) through the optimistic oracle.
Winner's profit = $25. Rake = 4% × $25 = $1.
Winner receives $25 + $24 = $49.
Loser receives nothing.
Orobas receives $1.

Voided or refunded game

Each player gets back their full stake. No rake is taken.
Examples: opponent disconnects before the first move and the game voids; a draw occurs by stalemate, threefold repetition, insufficient material, or the 50-move rule (chess); an event resolves to void by the operator.

Why this is different from a traditional casino

In a traditional casino, the house plays against you. The casino has a built-in mathematical edge on every bet — for U.S. double-zero roulette it's about 5.26%, for blackjack with basic strategy about 0.5%, for many slot machines 5%–15%. The casino wins on average; you lose on average.

Orobas isn't the house. Orobas is the venue. Every game on Orobas is between two players. One player wins; the other loses. We take a small commission from the winner's profit. The math of who wins is set by the rules of the mode (50/50 random for coinflip, skill for chess, real-world outcome for events) — not by us.

What that means in practice: if you play coinflip an infinite number of times, you lose 4% of your profit on each win. Over many games, that compounds to a substantial expected loss — the same way poker rake compounds in traditional poker rooms. We want to be straightforward about that.

Your long-run expected return

The math is easiest for coinflip. Let's say you flip $10 a thousand times against a fair opponent.

You expect to win 500 and lose 500.
On each win, you net $9.60 (after rake). On each loss, you lose $10.
Expected per-flip return: 0.5 × $9.60 − 0.5 × $10 = −$0.20.
Over 1,000 flips: expected total loss = $200.
That's a long-run cost of 2% of every dollar you wager (not 4% of every dollar — because you only pay rake on wins).

For chess, your expected return depends on whether you are better or worse than your matched opponent. ELO-based matchmaking tries to pair players of similar skill, so over time you should win about as many as you lose. If you are systematically better than your matchmaking bracket, you can have a positive expected return even after rake.

For events, your expected return depends on whether your probability estimate is better than the price the market is offering. If you can identify mis-priced events more often than you cannot, your expected return is positive net of rake.

What we do with the rake

Rake routes on-chain to a treasury program-derived account controlled by Orobas. The treasury funds:

Infrastructure: hosting, RPC, oracles, monitoring.
Engineering: the team that builds and operates the Service.
Customer support and KYC verification costs.
Legal, compliance, and audit.
Reserves against operational risk.

Treasury transactions are visible on the Solana blockchain at the treasury address (which we publish in the Terms of Service appendix on mainnet launch).

Verifying it for yourself

For every settled coinflip, the verification page at /duel/[id] shows:

The escrowed pot.
The rake basis points used to compute the rake.
The on-chain settle transaction (linkable on Solscan).
The revealed VRF byte and the parity-check math.
The winner's wallet address that received the payout.

You can confirm independently that the payout math is correct. Anyone can do this — you do not need an Orobas account.

Future changes

We may adjust the rake rate prospectively with reasonable notice. Wagers already in-flight are settled at the rake rate in effect at the time the wager was placed. The on-chain rake-basis-points parameter is operator-controlled but visible on chain; any change is auditable.