One thing trumps everything for me: Storytelling
The Ren'py format and similar are often the best fit for storytelling, but it doesn't have to be. HTML text games can work well too. Its not necessary about the images. I dislike needlessly complicated mechanics like RPGM and RAGS because they steal time and make it harder to navigate, but that doesn't mean I hate gameplay. Some of my favorite games are RPGM like Coceter Chronicles and Roundscape. One thing that really kills my enthusiasm is needless grinding, I'm here for the story. That doesn't mean that I'm impatient, a game can hold my attention with slow burn for a long time as long as its engaging, but I don't want it to waste my time.
The Ren'py format and similar are often the best fit for storytelling, but it doesn't have to be. HTML text games can work well too. Its not necessary about the images. I dislike needlessly complicated mechanics like RPGM and RAGS because they steal time and make it harder to navigate, but that doesn't mean I hate gameplay. Some of my favorite games are RPGM like Coceter Chronicles and Roundscape. One thing that really kills my enthusiasm is needless grinding, I'm here for the story. That doesn't mean that I'm impatient, a game can hold my attention with slow burn for a long time as long as its engaging, but I don't want it to waste my time.