Like others, I would have to point to the choice of making another sudoku as a critical flaw. When a game is the same game as every other, it gets very little buzz or word of mouth...unless it has some overwhelmingly strong new feature to add value.<p>Content items like art, storytelling, quantity of levels and pre-scripted events are mostly reflective of how video game development budgets tend to be proportioned against marketing budgets, where as the marketing budget gets bigger, more money is spent on making a lavish production that slightly outclasses the competition. These things help when a game has an existing audience that needs to mature into a more elaborate experience, but they have strongly diminishing returns on investment.<p>Software features like multi-player, solvers, hints and tutorials, puzzle generators, are all good incremental extensions that can get people's attention, and many of these features are relatively cheap compared to additional content. Unfortunately, all of the big, obvious features for incrementally extending sudoku have been covered - there's no chance of gaining a lot of new users in this market when it's so thoroughly saturated.<p>Monetization has also been saturated. Game monetization follows a pattern typical to innovative technology: Innovators can go pay-to-play if they're selling the privilege of a new experience. A good number of niche games can slip under the radar, making good profits for the innovator, but not enough to get attention. If the game is so profitable that it attracts a lot of attention, clones will appear and add incremental improvements, which pressures both price and quality. Eventually price collapses as free-to-play versions appear. However, free-to-play is _not_ the last step - open-source is. When people are hacking together polished, open-source versions of the game design, it's usually well past profitability, and sudoku is definitely in this category. (Exceptions to open-source as the last step exist, but are mostly related to the relative costs of content vs. technology)<p>Which leaves you with "create a new, sudoku-inspired game design." Game design is the underlying source of both profitability and popularity in the videogaming sector, but it means having design skills in addition to production skills - formulaic processes for making original, marketable designs don't exist. The vast majority of people in the sector understand either original(but unmarketable) or marketable(but unoriginal), but have trouble recognizing when a design decision and a marketing decision are related, and what the implications are. And since maximizing marketability is more likely to keep you in business, industry consensus always biases around it.