The full list is here and there are lots of them:
https://summerofcode.withgoogle.com/organizations/?sp-page=2

I think gamefromscratch.com just pulled out a short list of ones that were game-related there.

--bb

On Mon, Feb 24, 2020 at 10:05 AM rikki cattermole via Digitalmars-d-announce <digitalmars-d-announce@puremagic.com> wrote:
On 25/02/2020 6:43 AM, Panke wrote:
> On Monday, 24 February 2020 at 02:52:04 UTC, RazvanN wrote:
>> On Tuesday, 18 February 2020 at 05:59:47 UTC, RazvanN wrote:
>>> Hello everyone!
>>>
>>> In a couple of days we should find out if The Dlang Foundation was
>>> accepted as a mentoring organization for Google Summer of Code 2020.
>>> If we get accepted, I think that we should have a list of priority
>>> projects that we should propose to students. I have started tagging
>>> what I find the most useful projects with the gsoc2020 tag [1]. If
>>> you want to help in this process you can:
>>>
>>> [...]
>>
>> Unfortunately, Dlang has not been accepted this year as a GSOC
>> mentoring organization. Maybe we will have better luck next year,
>>
>> Cheers,
>> RazvanN
>
> Do we know why?

This is my guess:

https://www.gamefromscratch.com/post/2020/02/20/GSoC-2020-Organizations-Announced.aspx

Limited spots, somebody had to go.