All people need connections and responsibility. It's even more true for mental issues. Without those and a penchant for playing video games all day...that makes a very bad combination.
Take time to help him strengthen any social connections he has.
Does he have any responsibilities at all? It's hard for you to add any, since he is a grown man. But, since you do support him some, you could try requiring something in return for grocery money (housework in your home comes to mind, if possible, something he is good at so he can take pride in the work).
Also, take care not to give the illusion that you no longer have needs. This is very important for a lot of reasons. I can't think how to explain it, so I will give an example:
My brother's wife is schizophrenic. She's been hospitalized multiple times and suffers with depression and anxiety as well. Recently, my brother had a heart attack and almost died. He was in the hospital for several days being stabilized and then had a very strict diet to follow afterwards (he also had very uncontrolled diabetes--which was set off the heart problems). Everyone was so afraid that this was going to be too much and too hard on my sister-in-law. I commented that I thought it might be really good for her. ...and I was right! She's been very stable and has done extremely well helping care for her husband. People need to be needed. Sometimes when a person has so many life difficulties, everyone around them takes away the opportunity for that person to step up and help someone else. I think it's the worst thing that could be done. Connections to others are so important.
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So you know who just said that:
I am female, I am married
I have two children (one AS and one NT)
I have been diagnosed with Aspergers and MERLD
I have significant chronic medical conditions as well