Before getting into what modern indie games have done to innovate on the formula, it may be best to take a peek into the game that influenced them all to begin with. Rogue's popularity has largely faded away despite how many games claim to be Rogue-Lite, but many of the systems that were present in Rogue are defining of the subgenre to this day. These mechanics just happened to be fun while still maintaining extreme challenge that eventually they were adopted into the mainstream of indie culture.

Rogue is a dungeon crawling role-playing game in which the player takes control of an adventurer who must traverse multiple dungeons, taking on waves of monsters in order to eventually find the mystical Amulet of Yendor. However, what set Rogue apart from other dungeon crawlers of its time was the fact that each dungeon layout was randomly generated, meaning that the chance of getting the exact same dungeon as a previous run was slim. Once the character failed, they would also lose all progress in their run and be set back to another randomly generated dungeon, coining the term "Perma-death" in the process.

Rogue was created by two students - Michael Toy and Glenn Wichman - who dreamed of creating a text-based game much like the other popular games at the time. However, they also chose to add the random elements to their game in order to create a different experience for the users every time they boot up the game. The procedural generation of Rogue turned out to be a hit at the duo’s campus, and inspired the long list of games that would come out which tried to innovate on Rogue's formulas.

While other games had gameplay elements similar to Rogue, it was the release of this particular game that lit the spark of what would become the Rogue-Lite genre. Of the many Rogue-Lites to release, some of the most prominent ones which paved the way further were Hack in 1982 and Moria in 1983. In terms of more modern gaming, the game to kickstart the love for Rogue-Lites once again was The Binding of Isaac, which quickly rose to the top of indie gaming due to its incredible challenge along with perma-death and procedural generation, two elements taken directly from Rogue. Inspired by an earlier Rogue-Lite - Spelunky by Derek Yu - Binding of Isaac was an attempt at injecting the various mechanics of Rogue into the gameplay style of the original Legend of Zelda, and it was met with critical acclaim across the entire gaming world.

Following the success of Super Meat Boy, Edmund McMillen wanted to develop a risky passion project to work off a lot of the stress that came with working on SMB. Binding of Isaac was his creepy passion project, which was initially expected to tank by both of the developers. What actually transpired was nothing short of a miracle for the team - The Binding of Isaac was a raging success. The religious messages which were thought to be "career suicide" turned out to resonate with audiences, and the gameplay was engaging and addicting enough to hook people for ages. Binding of Isaac was one of the most difficult indie games of its time, but learning how to conquer the game was a reward for many, along with finding the greatest item synergies on their quest to defeat the monsters of Isaac's basement.

What McMillen thought would be career-ending turned out to be one of the greatest boons for the indie game community. Rogue-Lite popularity as a whole exploded on the release of Isaac, and it hasn't slowed down even a little bit. Many people in the gaming market were exposed to a relatively mainstream Rogue-Lite game, which would ignite massive interest in more games with the same mechanics as the original Rogue. Following the release of Isaac, other popular Rogue-Lites such as FTL: Faster Than Light and a re-released Spelunky showed that the Rogue formula could be spliced with other game genres - these games in particular, being strategy simulators and platformers respectively - and create an even more compelling gaming experience. To this day, Rogue-Lite titles such as Dead Cells and Flinthook are making rounds in the indie game community for being innovative takes on their respective genres while using the Rogue mechanics to further enhance the experience.

The traditional staples of Rogue-Lite games are losing all progress upon failure along with the extremely steep difficulty curve that most games possess. While this level of difficulty may seem like a turnoff to most players, fans of Rogue-Lite games are so enamoured with them because of the fact that the games can be brutal. Many fans would argue that traditional AAA games are becoming too easy, and being able to master the difficulty of a game that was beating you down around 20 hours ago is utterly satisfying. This is further cemented by the fact that most Rogue-Lites possess some form of progression - whether it's new characters, weapons, or items which synergize with one another to create an even more unique gaming experience.

Another reason that the Rogue-Lite formula may be so successful is the fact that it can be interjected into any other game with relatively high success. A concept as ridiculous as a Dance Dance Revolution Rogue-Lite game - ala Crypt of the Necrodancer - turns out to be far more engaging and fun than you might think, because of how seamlessly the mechanics work with the actual rhythm gameplay. Other genres such as side-scrolling shooters (Mega Man, Contra, etc.) are perfect fits for a Rogue-Lite treatment due to the fact that many of those games use difficulty and learning as a selling point. While not every Rogue-Lite is guaranteed to be a successful endeavor, it is certainly refreshing to see how many different styles of Rogue-Lite's can be made.

Cadence is an explorer who comes from a lineage of treasure hunters, each revered and famed before mysteriously disappearing or dying. Cadence’s father goes missing one day, and she takes it upon herself to search for him - leading her to a crypt which is controlled by the NecroDancer. The NecroDancer steals Cadence’s heart, forcing her every action to be dictated by the beat of his minions’ music. If Cadence wanted her heart back, as well as the location of her father, she would have to traverse the crypt and defeat the NecroDancer all while she makes sure that she doesn’t miss a beat and perish.

Conceptually, Crypt of the NecroDancer is rather odd as a rhythm-based Rogue-Lite game. However, the execution of NecroDancer puts it on top as one of the better Rogue-Lites in recent years. In order to control Cadence, the player must perform every action to the beat of whichever track is playing - taking damage whenever a beat is missed. Otherwise, Crypt of the NecroDancer plays as a traditional Rogue-Lite dungeon-crawler, but the nuance in its rhythm mechanic create gameplay that is both very unique and addicting. Each track has a different rhythm to it as well, meaning that the player must adapt to each new stage on the fly or learn the beats through multiple runs of practice (which are around 2-5 minutes on average). Crypt of the NecroDancer is one of the most unique modern indies to come out in years, and the difficulty and replayability cement it as an enjoyable experience as well.