It is a dangerous act in a country where graffiti can fetch eight strokes of the cane, more dangerous still because it parodies the leader of the ruling Lee dynasty. With a few deft applications of spray paint, Skope One finishes a pig-head depiction of the prime minister, Lee Hsien Loong, with a Nazi-styled SS logo on the lapel and an Uncle Sam-inspired banner emblazoned "Lee Wants You".

"We shouldn't be scared any more – it's about time something changed," says the 35-year-old artist, the founder of Singaporean graffiti. "We need to have this freedom of alternative speech."

Singapore is known worldwide for censorship and corporal punishment. But in the runup to Saturday's parliamentary elections more people have started to speak out against the clan that has ruled Singapore for almost 50 years. Parallels with the Arab spring are striking, even if revolution is not just around the corner.

Most murmurs of discontent can be found online: fears of reprisal are diminished for anonymous bloggers. On internet forums, blogs, Facebook and Twitter, grumblings about high housing prices, the widening gap between rich and poor, immigration laws and the salaries of government ministers (among the highest in the world) are hot topics.

The People's Action party (PAP) has been in power since independence in 1965, and is widely recognised as having turned this colonial outpost into a financial behemoth in a few decades. But it knows it has a battle on its hands. On Saturday, it will contest 82 of the 87 seats, up from 47 of 84 seats in 2006.

More than one in four voters in Singapore's 5 million-strong population, are under the age of 35, and the internet is a main source of news. For the first time, candidates have been allowed to campaign using social media, and the effect has been far-reaching: many Singaporeans say this is the most debated and politicised election they have seen.

Not all young people will be using their mandatory vote to go against the grain. Some, such as economics student and first-time voter Sofina Toh, 22, are swayed by the PAP's recent apology for past mistakes and promise to do better. "The PAP has done so much for Singapore – just look at the country now from what it used to be," she says. "Shouldn't we give credit where credit is due? They've promised to make changes. Maybe we can give them another chance."

Others are not convinced. "Fool me once, shame on you; fool me twice, shame on me," tweets a management student, Ong Rei En.

At political rallies, for which turnout has arguably been the highest in Singapore's history, the energy is electric. An estimated 50,000 people crowded into an outdoor stadium on Thursday to wave blue flags and wield inflatable hammers, symbol of the opposition Workers' party. As the crowd chanted for change, fists raised in hope, armed police watched awkwardly, the sweat on their brows betraying the night's humidity.

Rally attendance does not always translate to the polling booth. In 2006, despite large crowds at opposition speeches, the PAP won 67% of the vote. Many Singaporeans fear their ballots will be traced and their mortgages or jobs taken away if they vote for the opposition.

Asked if Singapore is an Egypt in the making, Skope One furrows his brow as he bundles his spray-paint cans into a backpack. "We don't want the same problems," he says finally. "But we definitely echo the same feelings."