If you have five spare minutes, Simon Sprint will fill them. Everything happens on one screen with patterns that speed up every level, down to 220 ms per flash, and the whole thing runs straight in the browser - no downloads, no sign-ups, no fuss.
Sound is part of the design - each pad has its own tone, and many players find they remember the melody of the sequence better than the colours. Turn the sound on once; you might be surprised how much it helps.
Nothing here needs a tutorial or a wiki. Controls are one gesture, the goal is one sentence, and the difficulty comes from execution rather than homework. That is exactly what a browser game should be.
Repeat the light pattern. It speeds up every level.
Simon Sprint is filed under Teka Shelf, and the decision comes down to one tag set: memory, reflex, pattern. Those three words are the whole reason it is not sitting somewhere else.
Mechanically it stays close to its tag set — memory, reflex, pattern — and does not add a second system on top, which is why it survives repeated play better than it looks like it will.
Keep it if you play in short bursts. It rewards a second attempt far more than a first, and the second attempt costs nothing but the tap.