Split Second - 1v1 Masked Flash Attention Duel
Split Second on FlagDuel is a free 1v1 attention duel run as a tachistoscope: a symbol flashes for 0.2 seconds at first and 8 milliseconds less for every point down to a floor of 0.09 seconds, a mask then covers it and four options appear, picking what you saw scores a point while a wrong pick locks you for 0.7 seconds, and the first player to 10 points wins the round.
A symbol appears for two tenths of a second. A mask drops over it - a scramble of shapes in the same spot - and then four options ask you what was there.
Two tenths sounds impossibly short and is not: the eye takes in a shape far faster than that, and the opening points feel almost unfair in your favour. Then the flash loses eight milliseconds for every point you score, down to a floor of 0.09 seconds, and somewhere on the way down it crosses the line between seeing a symbol and having an impression of one.
The mask is what makes this hard, rather than the speed. Without it the picture would linger in your eye long after the symbol had gone and you could read it at your own pace; the mask overwrites that lingering copy and leaves you with whatever had already been taken from it. A wrong pick locks you for 0.7 seconds, and ten points takes the round.
How to play
- Press START - the same symbol flashes on both boards, opening at 0.2 s.
- A mask covers it and four options appear. Pick what you saw; the flash loses 8 ms per point down to a floor of 0.09 s, and a wrong pick locks you for 0.7 s.
- First player to 10 points takes the round. Win 2 of 3 rounds to take the match.
Fair play
A real player from a new country every match. When nobody is free, you face a recorded run — a real person’s taps replayed, never a script.
Identical signals, targets, grids and sequences — and every click visible on both halves.
Every duel is free; accounts arrive later only to save your name on leaderboards.
All duels
Rewards
Win streaks forge belts worn next to your name: bronze at 3, silver at 5, gold at 10 wins in a row.
Every live win lifts your flag on the world board in the header — real duels only, practice matches never count.
Milestone wins will mint a shareable victory card with your name, flag and the story of the match.
SoonFrequently asked questions
What is a tachistoscope?
The instrument psychologists used to flash an image for a precisely controlled fraction of a second, usually followed by a mask so the eye could not go on reading it afterwards. Screens have replaced the hardware, but the method is unchanged and it is exactly what this duel runs on: a brief exposure, an interruption, and a question about what got through.
What does the mask actually take away?
The copy your eye keeps after the light has gone. A flashed image survives for a fraction of a second in a very brief visual store, which is why a 0.2 second symbol can be read at leisure if nothing interferes with it. A pattern in the same place overwrites that store, so the mask does not hide the symbol - it stops you rereading it after the fact.
Is 0.09 seconds too short for an eye to register anything at all?
Not at all, and that surprises most people. Recognition of a simple, familiar shape happens well inside a tenth of a second, and the floor sits there because that is roughly where accuracy begins to slide rather than collapse. The tenth point of a round is genuinely difficult; it is not a coin toss.
Does blinking at the wrong moment cost a whole point?
It can, and there is nothing to be done about it after the fact. Down at the floor the symbol is on screen for less time than a blink takes, so an unlucky one wipes the exposure entirely and leaves you guessing among four options. The only defence is noticing when your eyes are tired - blinks come in clusters, and so do the points lost to them.