I do believe their popularity comes from the games themselves. It started with all the developer of agar.io, who found some terrific mechanics that became immensely popular. The subsequent io games unblocked followed exactly the same key principles and consequently also became popular.
On the surface level, what these games share would be that the player starts in the weak/fairly powerless position. They may be easily demolished by many people other players, however if they be cautious, it isn’t too much to succeed. In most three games, the greater/longer/higher ranked players pose a greater threat than their newer counterparts. Importantly though, smaller players will take about the larger players with smart strategies. In agar.io, viruses could be split and targeted at the larger players. In slither.io, any player can definitely defeat a top player if they’re fortunate. And also in diep.io players can team together to consider the leaders. So from your perspective of a new player, with some effort and time they too can achieve the top. This is extremely alluring.
And I think this principle doesn’t just pertain to players themselves. When agar.io first was released, anyone felt that they had an opportunity to rise to the top. Youtubers started making videos in regards to the game, and then other youtubers believed that they too could become popular by making agar.io videos. Then, other developers felt exactly the same compulsion either to clone or make another kind of .io game that would top charts. So now .io games have become a phenomenon, which explains why rim sim still pop up and become popular.
Another thing how the games share is definitely a high depth to complexity ratio. That is certainly to say, there are many possible outcomes inside the game on account of quite simple controls and rulesets. In agar.io, all you want know is you move together with the mouse, split with space, and eject mass with w. With this knowledge, you can start to play. Of course there are lots of other activities to find out inside the game, like the truth that viruses can pop you if you’re big enough or special dexipky52 to turn into a good player, but the important thing is that this info isn’t necessary at the beginning and isn’t ever even shown to the player by means of a tutorial. The gamer is left to his/her own devices and might discover this data without needing all this piled on in the beginning. The controls for check out cool worm game here are even more simple. Mouse to move and space to improve. But readily available simple mechanics a lot of interesting scenarios pan out.