There is some debate about “the definition” of a roguelike. Some argue that a roguelike must meet a list of essential features, but even those features are different depending on who you ask. What I think we are missing is the feel of the genre. It’s easier to feel than you would think. When we see a platformer or a RPG we can feel it from couple of generic features. Platformers have platforms you jump on and role-playing games have a RPG system with character classes, stats etc.
I feel that the essential feature of a roguelike is a top-down tile map of the game world with turn-based tactical gameplay. The gameplay should also have some role-playing features, but to increase the feel it better have a complex role-playing system similar to Dungeons & Dragons system. When we look at a roguelike as subset of role-playing game it’s easier to get the proper feel about it. The difference between a regular RPG and roguelike is randomly generated game world and permadeath, although it’s possible for a RPG to have some random features and permadeath. In similar manner some roguelikes can have static locations and various ways to restore the character after death. Even the classical roguelike Nethack has ‘bones’ for giving back some items from a previous character.
ASCII graphics makes the game feel more like an old school roguelike, but it’s not a decisive feature. The reason roguelikes had ASCII graphics was mainly a technical limitation and in broad sense ASCII tiles are “graphics”, too. They are just a way to represent something. Some roguelikes implement both ASCII and tile modes which work interchangeably and make no difference to the gameplay itself.
It’s quite easy to feel when the game is not a roguelike. It may look like one, but it’s often missing the complexity and size of so called major roguelike. These games have their own genre title as roguelites, but in some cases it can be argued if they are simply adventure and/or (action) role-playing games with some roguelike features. Games like Spelunky are sometimes thought as roguelikes, but for me Spelunky feels a lot like platformer game, it just has randomly generated levels. Random generation is not a feature only for roguelikes, it can be used in all genres. What makes it a feature of a roguelike is the proper context.
The problem of a flexible interpretation has been a saturation of the genre with games that in fact are not roguelikes. Some developers use the genre name in marketing, because it’s easier to get visibility for your game when you have a clear genre for it. When even developers think their game is a roguelike the genre has regressed from major roguelikes as standard to something else. It’s “acceptable” to define your game as roguelike when you have one or more features of a roguelike taken out of context.
Let’s be honest. We can all feel when the game is a roguelike. It’s all that matters, for both developers and players.