This poem made me feel and think more than I'd like to admit (it's a good thing).
I will preface this comment by saying that this can be taken so many ways, these are just my thoughts.
The way you dressed up these metaphors are beautiful and sad. I do believe that the first stanza could be about mental illness and the way this person see themselves with it. This person sees themselves as this callous or cold person on the Inside but outside perhaps they try to hide it as best as they can. They have always felt the nighttime is better because it connects to how they feel. They either have never felt the light or haven't in a long while.
This person feels broken, and I don't think someone hurt them per say- but perhaps they feel guilt about something that was an accident and not their fault but they feel like it is.
I love the twist at the ending parts, because now they feel happy about what they have done, or perhaps it is a relief that this person has died. I love the questions at the end as well, because it changes the story completely and it's not a bad thing at all.
Perhaps this person was a murderer and at first they felt guilty but now they are slowly realizing that they can move on. Speaking from the title I imagine 'play' as a child thing. So maybe someone died from this person's childhood?
The thing I love is the attention to detail around each stanza, especially the grave part because you have wilted flowers and I imagine a grave being tied to sadness. The way you can have different meanings is excellent as well.
I feel like I want to delve into a thousand different thoughts I have reading this, but this is too heart-wrenching. Mentioning the instruments made me think of times when my spirit was so low, I didn't even want to play the piano or sing, because it's like that part of you that is empty. Those two lines about the organ and guitar made me feel like this goes even deeper, that your spirit is broken and these little things that would bring you joy, give you purpose, they're not present. Literal pieces of you can't properly function anymore.
That question of "Do you?" is a like a plea to understand why you are grieving, or perhaps with you being happiest there gives you the chance to ask and wonder and feel. I read others' thoughts too but the way I took it is that you feel better at the grave. More complete. Because living a life without them, not going to their grave and visiting them would be letting life continue and accepting there's this opportunity to move on. That's how I could see it at least but like Jamie said, there are so many different paths this could take. But it's personal to you and I just feel a field of grief in this.