Im doing level design on nax. Deciding what to add to the game to mix it up, as currently I have a bunch of interconnected areas with monsters to kill, coins to collect, chests to find. I can see it getting stale pretty quickly. Need some variety.
I did a lot of brainstorming yesterday and here's some things I've come up with.
-Light platforming (eg: areas where spikes come out of the floors and you're to jump over them, or climbing up the side of a cliff by jumping from platform to platform)
-Special locked chests, which contain rarer items in them, but require a key to open.
-Destructible objects, so that there's some interactivity with the world, AND gives tactical options. (eg: cut the trees down to reach enemies easier, or leave the trees up, making it harder for the enemy to get to you)
-Some water traversal, where your options are limited to swimming or jumping, just to change the pace. And water sections might have monsters which you can't attack, but you can use the snatch ability to teleport them out of the water and kill them on land.
-mud/snow/shallow water - areas where your movement is slowed down, dashing is impossible. and monsters are sometimes hiding underneath.
-tall grass - areas where monsters can hide in, but you can also hide in to avoid detection from monsters. possibly leading to some pseudo stealth sections if the enemy is too powerful.
-Key puzzles/pushing object puzzles.
-implementing "sidequests" where mid-mission, there might be an NPC who asks you to do a task on that mission, being completely optional, but you get a cash/item/card reward. (eg: clear out monsters in a room, or retrieve x item, kill a miniboss, find lost NPC, etc)
Stuff like that should really make exploring levels more exciting and varied.
Thinking up these ideas is one thing... Implementing them is a whole different ball game.