Thinking about continuing this novel with like the cliché dungeon stuff, with a status window, stats, and skills. Maybe there might be something like classes and class specialization unique to the person and their skillset. I was also thinking of having the portals be some type of dungeon. With a very small chance of some of these dungeons having themes such as destroyed worlds that were overrun by calamity. These unique dungeons are going to have stronger opponents and a more threatening environment. Dungeons are going to be able to be explored and adventured by people who enter. Every dungeon is going to be different and are going to have unique environments and enemies. The goal of the adventurers is to defeat the boss and any other monster they might find inside of these dungeons. Doing so will result in the collapse of the dungeon. The collapse will occur in a set time period and will be indicated by some type of timer. Monsters will scatter into these kinds of light particles when killed or defeated and leave behind loot corresponding to the type of monster or creature they are. Valuables and items are gonna be able to found at the end of every dungeon after defeating the boss in a chest or something, they might also be found scattered throughout the dungeon in secret areas. The beginning of the story might consist of almost instantaneous dungeon breaks just to start it off then after these first wave of breaks it'll transition to normal speed. Since modern weapons are a thing I was thinking of making most higher grade or rank enemies be invulnerable to those types of weapons. I was also thinking of making modern weapons be impossible to bring inside of dungeons or have them break down inside upon entry or something. Everyone might start off with a weapon given to them at the start of the story, might be something like an iron sword. I think that weapons are gonna be those that are crafted and made from ores, or some that are found inside of dungeon chests. Weapons might be made and crafted by people who receive classes like blacksmiths. Grade of weapon depends on skill of the blacksmith as well as the quality of the ore. Weapons are going to be melee weapons, might also be wands or staffs to boost stats of magicians. There might also be classes like alchemists to craft potions as well. Exact location of the story would be fictional and just be a made up place.