This sounds potentially like making excuses because I think those extra things are easier than writing. Taking and posting screenshots here is quite easy even with a slower process (google what the hotkey is, save screenshot to a file, then upload). I have ctrl-s bound to screenshot a screen region to my clipboard which I can just paste into a forum post without dealing with any files. Opening a video game is also easy though doing actual testing about how one of the in-game words works could definitely be harder.
If you think the writing part is easy, write a lot more! How about you try to write 5 posts per day for a month? If it works, great. Otherwise you can maybe get information about what’s blocking you.
One thing you might potentially get stuck on (idk) is being really afraid of missing one day or giving up if you do (related to perfectionism). In general, it’s fine to treat every day as meaning 5+ days per week, so there’s some flexibility in case you miss days. Don’t skip days just because you’re allowed to though. You can skip because you want a break (though you said you can write fine when tired, so if you need a break that’d be relevant information), or you forgot, or you were busy, or you really wanted to do something else, but don’t just be like “I already wrote 5 posts this week so I’ll skip the next 2 days now b/c i don’t need more posts”. Or, worse, don’t skip the first 2 days of the week since you don’t have to start yet, which would remove your margin for error at the beginning instead of wasting it at the end, so then you wouldn’t have spare days if stuff came up and you were busy.
That stuff is objectively not very hard. The second link is just broken because the colon is being included in the link. I recommend just having a space or newline before and after links or doing them in markdown format (which you can type or get by writing the words, highlighting them, then pasting the link, or use cmd-k or click the link button).
Maybe you just need to practice link (and quote?) formatting for a bit and learn about it better so it becomes easier and you gain more confidence about how it works. It’s something you can master pretty quickly.
FYI in general links don’t need to be pretty, like if it shows up as a URL instead of a page title that’s ok.