It starts off similar to the story "In One Piece with the Ironman Armor by Shihao777" with the person getting ironmans nanotech armor in the first item gacha and/or starter box but the starter world I think could be interesting to be in is Danmachi just because but it's up to whoever writes this story if they go with it and later the world's of Marvel and DC or a Marvel and DC mix all three or two depending the mc will permanently travel between participating in each worlds story. So the system works this way the person is able to purchase any technology from anywhere he could buy a lightsaber from Star Wars or a flintlock from One Piece anything can be considered apart of technology, but it's not cheap costs a lot of points or money whatever the writer chooses, they can also purchase the knowledge for technology from different worlds they can purchase the whole tech tree of the different worlds it also unlocks the option to purchase materials which is cheaper than buying the finished product to create the tech for example if the material doesn't exist in the world the mc is in like the Marvel metal vibranium. But the tech trees are much more expensive so most of these will be received through missions, or the gacha where the mc can get the tech, knowledge, materials, or other things like travel tickets and Mission travel tickets. The tickets come in three different types the normal travel ticket where the mc gets to go to a different world for a set period of time in which he can travel around gathering items, knowledge or even allies, he might come across a surprise mission or 2 if the mc is lucky and when the timer expires he and people who chose to tag along are transported back to the world the mc was in before he used the ticket. The permanent travel ticket is just that it unlocks a world the mc can travel to and from whenever they want and stay for however long they want this is how he unlocks the Marvel and DC worlds. The last ticket is the mission travel ticket where the mc will be given a mission pertaining to the world a strict deadline and will be restricted to certain tech in the mcs system, an example I thought of was in One Piece the mc comes in a few weeks or a month or two before Ace's execution and the battle between Whitebeard and the marines the mission is to save Ace and keep him, Whitebeard and Luffy alive and escape he will also have bonus objectives like defeat the marines to rescue Ace instead of just escaping to harder bonus objectives like wipeout the world government of One Piece and maybe others like objectives that pertain to the story during the few weeks or months before the battle happens, the mc if he instead just stops Ace from being caught he will complete the mission but will get a low mission rating and lose out on bonus objectives that all could unlock tech trees, all while only having access to our earth from the past to modern day tech and whatever single person items he prepared before coming to the mission world, and what I mean is the system will give the mc a certain amount of items to use so he can have any number of weapons to use summoning one whole fleet of military ships to access to a nuclear warhead but there will be limits like only one nuke but he can buy more but his mission rating will be influenced by it.