The US Twitch streamer rose to fame playing survival game Dead by Daylight, where he was known for his positivity.
The game’s community rallied around him following his diagnosis and set up the Light in the Fog Foundation, raising $270k (£216k) to support his care.
In a reference to his catchphrase, the foundation said Puppers was “forever in our hearts, eternally comfy”.
Puppers, also known as Max, would end his streams by telling fans to “stay comfy, because if you’re comfy, you’re winning”.
The streamer was diagnosed with ALS – the most common form of MND – in 2020.
It affects the brain and nerves and causes weakness that gets worse over time, according to the NHS. There is no cure for the disease, but there are treatments to help reduce the impact on a person’s daily life.
A post on his Twitter page confirmed his death, saying he “loved you all so very much“.
“Thank you for all of the love and support throughout his career – making you all happy is truly what he lived for,” it said.
‘A beacon of positivity’
When Max was diagnosed with ALS, his friends – known by their online usernames Eshleee, Sunshine and Silver – “moved across the country” to provide care and support.
“Being his caregiver as he fought this absolutely awful disease was the biggest test and the biggest joy of my life,” Sunshine told the BBC.
“I will never forget him, and a piece of my heart will remain empty without him.”
Silver said they “will always remember” Max’s laugh and playing Dead by Daylight beside him, and Eshleee called the streamer “a beacon of positivity”.
“I can’t think of a single person who has had a greater impact on my life or the lives of so many,” they said.
“I wouldn’t trade a second of these last two years I had with him for anything.”
The three said they were “devastated” when Max was diagnosed, and set up Light in the Fog to help.
More than 150 Dead by Daylight streamers collaborated in a multi-day event to raise money for his treatment and care, which was boosted by endorsements from online personalities including MrBeast – the most subscribed YouTuber in the world.
The group are now asking the community for additional money to help cover his funeral costs, as well as outstanding medical costs from his treatment.
There has been an outpouring of support from the wider gaming community, which has called him a “true gaming champion” and “a kind soul we didn’t deserve”.
The developers of Dead by Daylight, who had previously added an item to the game in honour of him, called him “one of the brightest lights in The Fog”, a feature which helps players stay hidden from each other.
Meanwhile, hundreds of posts from fans responding to the news echoed Puppers’ signature sign off. “Rest easy,” many of the posts said, “stay comfy”.