Game of Thrones returns to our screens on April 25 — and to stoke our excitement, the first trailer for season six has been released.

(Warning: Trailer contains adult themes and is only suitable for over-16s)

Season five felt like a continual power shift, with major contenders for the Iron Throne wiped out, the Lannisters on their knees, Daenerys captured by Dothraki and the seemingly unstoppable rise of the High Sparrow.

Jon Snow was betrayed in the worst possible way and despite Melissandre's scheming, the Baratheon campaign was lost.

First look pictures from Game of Thrones season six

Today HBO released the first full-length trailer for Game of Thrones season six, previewing a series that looks even bloodier than the last.

Accompanied by the chilling Wicked Game by James McMorrow, the clip gave a glimpse of what key characters face this season, the aftermath of last season's shocking finale — and war.

Here's five things we learned:

Jon Snow is gone for good

Brenock O'Connor, Kit Harrington as Olly Hamlet; Jon Snow
Brenock O'Connor, Kit Harrington as Olly Hamlet; Jon Snow

To stop the endless speculation about Jon Snow and if his death really was the end of his character, the trailer opened with a shot of poor Jon, dead in the snow, with the words "He's gone." That's that then. But what does this mean for the watch? I have a feeling without Jon's levelheadedness it's all going to descend into chaos.

The Lannisters want revenge

Nikolaj Coster-Waldau as Jaime Lannister and Lena Headey as Cersei Lannister – photo Helen Sloan/HBO

Season five was tough for the Lannisters, particularly Cersei and Jaime. Cersei was arrested and imprisoned by the High Sparrow, and had to endure a brutal walk of shame back to the Red Keep. She still faces trial — but the trailer suggests she has other ideas. "I choose violence," she purred, back to the strong matriarch we love to hate.

Dean-Charles Chapman as King Tommen Baratheon, Nikolaj Coster-Waldau as Jaime Lannister and Nell Tiger Free as Myrcella Baratheon – photo Helen Sloan/HBO

Meanwhile, Jaime saw his daugher Myrcella murdered by Ellaria, and returns to King's Landing this season having failed his mission and lost his child. But he seems determined to have his revenge — as he says to Cersei: "Everything they have taken from us we're going to take back, and more."

Melisandre is lost

Possibly the most hated woman in the series, Melisandre ended season five having burned Stannis' daughter alive and wrongly predicted the victory of his army over the Boltons. Stannis and most of his men died in a bloody massacre, with Stannis dispatched by Brienne, who finally had her revenge for Renly's death.

Carice van Houten as Melisandre – photo Helen Sloan/HBO

Now Melisandre has nothing — her 'king' is dead, her army gone, and all of her child-burning and dark magic was for nothing. "The great victory we saw in the flames... all of it was a lie," she said. So what now for the Red Woman?

The High Sparrow wants power

Having taken down Cersei, the Tyrells and recruited a small army of devoted followers to carry our his bidding, the High Sparrow's mission to cleanse King's Landing of its crime and immorality gained pace in season five. And with Cersei and the Tyrells set to face his judgement, he could seize real power in King's Landing — can the Lannisters stop him? "Everyone of us is poor and powerless, yet we can overthrow and empire," he said.

But the Lannisters have their new, Frankenstein-esque secret weapon...

Isaac Hempstead Wright as Bran Stark and Max von Sydow as the Three-Eyed Raven – photo Helen Sloan/HBO

Bran meets the White Walkers

It was only for a brief moment, but it was in the trailer: Bran, taller and no longer paralysed, stood alongside the leader of the White Walkers. Oh god. Nothing good can come of this. We last saw the terrifying undead army as Jon and the men of the Watch fled from them their numbers growing as their victims transformed to join them. What is Bran doing with them? Will he be a victim? Gulp.

Game of Thrones returns to Sky Atlantic on April 25.