KIGALI - Rwanda on Sunday commemorates the 25th anniversary of the genocide in which at least 800,000 mainly Tutsi people were beaten, hacked and shot to death in a hundred days of slaughter.

A quarter of a century on, the country has recovered economically but the trauma casts a long and dark shadow over the country.

On Sunday, as has become the tradition every April 7, the day the genocide began, President Paul Kagame will light a remembrance flame in the capital at the Kigali Genocide Memorial, where more than 250,000 victims are said to be buried.

It marks the beginning of a week of commemoration activities, and the start of a hundred days of national mourning.

In the afternoon on Sunday, Kagame, who led the rebels that chased the genocidal killers out of Rwanda and has been in power ever since, leads memorial commemorations at a ceremony at Kigali's main football stadium.

The Amahoro National Stadium —"peace" in Rwanda's Kinyarwanda language—was used during the genocide by the UN to protect thousands of Tutsis from the massacres on the streets outside.

The Hutu forces, members of the old army and militia forces called the "Interahamwe", had been cheered on by blood-curdling anti-Tutsi propaganda that began on April 7 1994, the day after the assassination of President Juvenal Habyarimana, a Hutu.

Kagame, then 36, was a rebel general when he led the mainly Tutsi Rwandan Patriotic Front (RPF) into Kigali on July 4, and drove Hutu extremists out of the country.

Rwanda has changed nearly beyond all recognition since then.

But Kagame's rule has been at the helm of his nation ever since, steering the small, landlocked nation through economic recovery.

Growth in 2018 was a heady 7.2 percent, according to the African Development Bank (AfDB).

This boom has been largely boosted by the help received from an international community pained by its failures to stop the genocide.

"In 25 years, the things that we've been able to accomplish are really extraordinary," said Bruce Muringira, a 24-year old working for an advertising agency, and who like nearly two-thirds of Rwanda's 12 million people, was born after the genocide.

"I think we've evolved very much in such a short time."

Huge challenges remain, but the people are hopeful.

"We still see today that it is not perfect," Muringira said.

"But we're putting in the effort to find a way to live harmoniously."

For a people left divided by the bloodiest of legacies, reconciliation has been key.

Rwanda has banned any reference to ethnicity in public life.

It has prioritised justice for the genocidal killers, especially through the mass actions of the community courts, known as "gacaca", in a bid to rebuild relations between communities.

But the wounds of the tragedy have not all not healed. The reconciliation is far from perfect.

For families of victims, forgiveness remains difficult, when the bodies of their loved ones have not been found, and when many killers still evade justice.

Kagame is credited with overseeing rapid economic development in Rwanda after the genocide.

His successes earned him the status of model leader.

However in time, his iron-fisted rule—seen as needed to impose order from chaos—gained many critics.

Kagame's leadership was seen by those in the West as flouting freedom of expression and muzzling opposition.

Opposition to Kagame was silenced, or driven into exile.

He was re-elected for a new seven-year term in August 2017 with nearly 99 per cent of the vote.

Constitutional reforms adopted by referendum in 2015 would potentially allow him to stay in power until 2034.

But times might be changing, a bit.

Kagame, now 61, has been seen to be loosening control somewhat, perhaps aware of the questions about what will happen when he, someday, leaves power.

Some jailed opposition leaders have been released.

"Kagame sees it as prudent to shed off his old narrative of being autocratic and overly intolerant to opposition," said one Rwandan political commentator who asked not to be named.

"Don't forget that as time goes by, he is becoming more cognizant of which legacy he wants to leave behind."

Frank Habineza's Green Democratic Party, became the first opposition party to enter parliament last year, winning two seats in elections.

"I think the ruling party is no longer overly intolerant to opposing views. Over a period of time they have started listening to our views. Our manifestos have been now considered in government projects, not as before when they were ignored."

Several African leaders are expected at the ceremony, while former colonial ruler Belgium is sending Prime Minister Charles Michel.

But French President Emmanuel Macron is not attending, citing scheduling problems.

France, which Rwanda accuses of being complicit in the genocide, is sending Herve Berville, a 29-year old Rwandan-born member of parliament in Paris.

Perhaps most conspicuous by his absence will be former ally Ugandan President Yoweri Museveni.

Kigali now accuses Uganda of sheltering Rwandan rebels on its soil.