Is a bristly grey moustache a telltale sign of a Reform candidate? Is pink hair a giveaway for the Greens? Perhaps a sharp suit is the best telltale for the Tories – or spectacles and a rucksack for Labour?

Players of a viral politics game have been finding out that it’s never that simple to judge the colour of a candidate’s rosette just by how they look. The game, invented by Sam Hamill-Stewart, challenges players to look at pictures of local election candidates and guess their party affiliation.

The game, Guess the Party, was being shared across Westminster and among party activists on Thursday – and statistics show how hard it is to guess the party a candidate is standing for.

More than 3.9m guesses had been taken by the time polls closed on Thursday night – by about 134,000 people.

Before he launched the game, Hamill-Stewat removed some profiles that had a party logo in the background, sourcing the pictures from Democracy Club. A red tie can be a giveaway for Labour, but it can also be a red herring.

According to the game’s statistics, Green candidates are the easiest to identify, guessed correctly by 37.5% of players, followed by Reform, on 35.4%. But Liberal Democrats were the trickiest – correctly guessed by just 15.2% of players.

Some candidates had particularly high rates of correct guesses. Jacky Carr, a freelance theatre producer and artist standing in Broxborne, was guessed correctly as a Green candidate by 91.3% of players, and Alan John Outlaw, standing in Keighley East, was correctly guessed by 80.7% of players as a Reform candidate.

But many candidates did not conform to stereotypes. Martin Radbon, the Green party candidate for Erith, was guessed correctly by only 1.7% of players – most believed he was standing for Reform. Laura Caroline Harrison, standing for the Conservatives, also confused players who might have been thrown by her distinctly non-conservative purple hair.

She was identified as a Tory by only 2.5% of players, many of whom believed she was standing for the Greens.

Colourful hair was a running theme of mistakes. Of the top five candidates incorrectly identified as Greens, four had pink, red or purple hair, but they were in fact standing for the Conservatives, Labour or the Liberal Democrats.