Play PS2 online with a friend

Two people, two browsers, one match. Each of you runs the game on your own computer, and Retrario keeps the two games in step.

Before the first match

1. Make an account. Sign in from the hub or the Play online screen with a username (3 to 16 letters, digits or underscores), an email address and a password of at least 8 characters. Playing alone needs no account; online play does.
2. Add your friend. In Community › Your friends, search for your friend's username and send a request. Once they accept, each of you sees when the other is online. Until you sign in, the hub says “Sign in to see your friends online”.

Start a match

Open Play online and create a match: you get a match code and an invite link (the page address with the room in it). If your friend is online, press Invite next to their name and they get an invitation to join. If the hub says “None of your friends is online right now”, send them the code or the link instead: any signed-in player can join with it. Both of you press Ready, then the host presses Start. A small text chat sits in the room while you wait.

How the two games stay together

Each browser runs the full emulator. Only the controller inputs travel between the two computers, over a direct WebRTC link between the browsers, peer to peer. When the two networks block a direct link, the match can go through a relay server; the room shows “relay ready” when one is available.

Every input is played a few frames after it is pressed, at the same frame on both computers, so the two games stay identical. Every 50 frames the two games compare a check of their state; if they ever differ, the match ends and says so.

What makes a match smooth

• Two capable computers. Both should meet tier 1 on the requirements page: the slower computer sets the pace for both.
• A good link. A wired connection or good Wi-Fi on both sides. Distance adds delay.
• A delay that adapts. The input delay is picked from three seconds of pings before the start, raised when inputs begin to arrive late, and lowered at a pause or in the menus when the link allows it.
• Reconnection. A dropped link pauses the match: the browsers reconnect, check that both games are still equal and carry on. If the link does not come back within about 20 seconds, the match ends.

In the project's tests over a simulated link (80 ms round trip, jitter, 0.5 % packet loss and five-second cuts), no match ended and the two games never diverged.

After the match

The end screen offers Rematch (both press it), Back to lobby or Leave. There is no ranking and no matchmaking with strangers: you play with the people you add or send a link to.

Play now Chrome or Edge on a computer, nothing to install.