Summary It's probably fine according to Sheikh Uthaymeen's Fatwas. I don't particularly follow him, nor am I a hardcore Uthaymeen air conditioner, but you can read the whole and the sources I give to make sure yourself.
Long answer I am not exactly into creating images of anything, I am mostly into the programming part of stuff, so I am unfortunately no expert on this, but I can give you some hadith, but more explanation after them, because it seems these are easily misinterpretable.
Ibn 'Abbas (RA) reported that the Prophet (ﷺ) said: "Every image-maker will be in the Fire, and for every image that he made a soul will be created for him, which will be punished in the Fire." Ibn 'Abbas (RA) said: "If you must do that, make pictures of trees and other inanimate objects." (Reported by Muslim, 3/1871)
'Abdullaah ibn Mas'ood (RA) reported that the Prophet (ﷺ) said: "Those who will be most severely punished by Allah on the Day of Resurrection will be the image-makers." (Reported by al-Bukhari, see al-Fath, 10/382).
Abu Hurayrah (RA) reported that the Prophet (ﷺ) said: "Allah, may He be exalted, says: 'Who does more wrong than the one who tries to create something like My creation? Let him create a grain of wheat or a kernel of corn.'" (Reported by al-Bukhari, 10/385).
But mostly, this seems to be talking about idols or portraits. The Prophet (ﷺ) would prohibit a nation of people, who have just come from polytheism and idol worship, strictly from anything even remotely similar to idols. There was a Fatwa I found from Sheikh Salih al-Uthaymeen:
With regard to stuffed toys in which the image is not clear, even though there are limbs, heads and shoulders, but they have no eyes or noses, there is nothing wrong with them because this is not competing with the creation of Allah.
Basically, he's saying if it's something with features that make it look like a being, but it has no facial features, then it's fine. I'd rather take the word of Sheikh Uthaymeen (RA) over many others who are too strict on this (looking at islamqa.info).
While making sure I was answering what was right, I stumbled upon many of them claiming that photographs are unallowed, and this and that are all not okay apparently. Allah wouldn't burden us as He says in the Qur'an, and idk how they can possibly live without a passport or an ID (which has a picture of them).
You can find more about it here, which are Fatwas by Sheikh Uthaymeen, which, in summary is as follows: It's permissible to have images, as long as it's the following:
- Unrealistic images (such as cartoons).
- Images without facial features.
- Images of a Sheikh (on TV, phone, etc.), as it is for spreading guidance.
- Coins with images.
- IDs with your image.
I'm not exactly sure as none of these directly mention pixel art, though cartoons are digital and are hence pixels, but by these I'd say your pixel art is fine, but of course (for safety reasons) Allah knows best, and if anyone finds I am wrong, please, correct me. Jazakallahu Khair.
As for the cartoon images that you mentioned which appear on televisions, if it is in the shape of a human, then the ruling of looking at them is that it is permissible, does it follow (i.e. look like) a real image or not? And the closest (to the truth) is that it doesn't follow (i.e. look like a real image). And if it resembles a non-human, then there is no harm watching it as long as it is not accompanied by an evil deed (such as) music or its like, and as long as it doesn't keep a person away from doing the obligatory (deeds).