What are the best ways to design levels that offer different experiences each time?

I like the metroidvania approach of what I tend to call the ouroboros effect. I’m a big fan that a reward of exploration should be circling back to previous areas you’ve already explored, but from previously blocked paths. That feeling when you open a random door and it takes you back to the first level. The random dungeon in a castle that takes you to a secret area in a previous level. The penultimate gym badge which circles back to the final gym town… in the first city. I’m a big fan because when you circle back, its a reward in-of-itself.

One of the best examples I was impressed with that had "enjoyable replay ability" and "clever level design" was the old PC game : LEGACY OF KAIN SOUL REAVER. Your character had the ability to regularly phase from 1 realm into another (reality to ghost/spectral realm). The scenery often morphed into another version (passage of time) which added subtle changes in the landscape to allow the player to reach or discover new areas.

But understand that not all procedural generation is born equal. Try to have a clear concept of how and why procedural generation affects the play of your game (such as different distributions of goals, enemies, encounters, etc) and distinguish that from procedural generation intended to enhance veracity of a simulation (such as weather, trees, etc). Each has their place, but only the former is meaningful to game design.

Scale the game mechanics with the player’s progression. Introduce more complex versions of the mechanics they have already learned or discover entirely new mechanics. These mechanics allow access new areas, secrets, and content that were previously hinted at or inaccessible in the earlier levels. Moreover, by allowing multiple paths or methods to reach these new areas, the game encourages the player to experiment and adopt different strategies with each play-through.

Procedural generation in level design can be a great tool if set up correctly. Think of the rules of your level design when creating your tool. Do you want a layout with dead ends? A single opening? Fully open? Art heavily influences player experience or a level design too, so consider that too. Endless Dungeon utilizes procedural generation in their levels; sometimes it leads to great player experiences, other times not so much. An interesting approach is implemented in Hades, where the level design of a “room” is fixed, but the ORDER in which you experience the rooms is somewhat randomized. It works for their specific gameplay where the players are expected to replay the game 100s of times potentially “mastering” each room’s layout.

Giving the player a choice on how they’re moving towards their goal infront of them using different options physically laid out infront (or even behind) them can lead to great emergent gameplay. Let’s take the mobile game “Rumble” for example. Most levels allows the player to direct their minions towards certain lanes and even change their lane direction or change the elevation of their minions. This works in tandem with some of the core mechanics of their game where enemies can deal more damage from an elevated position. The player can reach the same goal by spawning and directing minions over several lanes and elevations creating emergent gameplay backed by strategy based on core mechanics.

When it comes to player choices in a level, it means providing different opportunities for the players to choose how the scenario will be played out based on their choices. Each provided opportunity needs to have a reason of being there, could be purely narrative driven or how the layout is structured in a way that it is there. They need to be somewhat readable even when they happen to chance upon it, framing and composition within the environment plays a big role when it comes to that. A good simple example is how we built the locations using the 360 approach within most of the Assassin's Creed games. We provide players with different opportunities depending on which angle they will be coming from towards the location.

Also don't rely on variation that only affects a simulation's veracity (such as weather) as its value will quickly be perceived as trivial by players. Oftentimes variation needs to be "chunky" rather "subtle" for players to interpret it as changing play.

I love the usage of having emergent gameplay especially in the open world setting where you allows different systems and player mechanics to interact with one another, this gives the player a lot of opportunity to experiment and test out what are the things they can do, and usually when they figure out stuffs on their own, they feel smart about it, and in return being more engaged, as the world is providing the feedbacks and giving the outcome they would expect based on their actions. We developers are usually the one that comes out with the rulesets when it comes to the systems and mechanics, ensuring the consistency of the feedback pattern and loop is very important for them.

Hades sets a stellar example. Players decide the room types they enter, influencing their passives and bonuses, compelling them to adapt their gameplay. With randomized maps and skill options, each playthrough offers a unique experience, making it an exemplary rogue-like game. What better genre to experience dynamic gameplay in repeated sessions than a rogue-like, right?

At the end of the day, you have to balance your design between a curated experience and something that's fully emergent and fresh every time. Different players like different mixes of these things, and different games call for different approaches. One isn't good or bad design. Consider games like Far Cry that are extremely emergent compared to The Last of Us. Different experiences for different kinds of players. Generally you'll want some of both for most games. Emergence gives you the memorable moments Pele talk about, while experience curation gives you compelling overall narrative that people remember.

Hey do your best. But once more if you have your story down, then you should be able to create some nice Alternative situation depending on how you have designed the game, I have a question why dose the world need to chage if you die.