The MC enters a world he thought only fiction till recently. (Whatever world is up to the author. [Don't do Marvel just because I'm using it as an example here because of my preference for it])
He enters armed with a system that expires when he turns 13 / becomes a teenager.
This system is more like a gacha system than others but with restrictions like;
- can only roll once a year
- a literal year (12 full months) would have had to pass before the option to roll be omes available upon which you can roll within that new year and only that year.
Should you miss the roll for a year, you won't be compensated (meaning if you have 13 rolls and you miss one, you only have 12 left).
- rewards don't feature summons (summon animals from Naruto, fair-formed demons from Bayonetta, pokemon, digimon, Bakugan, power ranger mechas and any other summonable gundams, elemental and celestial spirits, Yu-Gi-Oh and any other like it etc.)
- this is an extension of said previous point above, it won't give you living creatures so this extends to tools (equipment like armor or weapons) that are alive (either by magic and/or A.I science).
So if a reward was given that had intelligence to it, the intelligence will either be stripped from said reward or you'll be given a chance to redo that draw.
You can however only redo once so if the redo gives another reward with intelligence, then it will forcibly have it's intelligence stripped away and/or made weaker.
- it won't give you the energy and everything you need to use a reward from it, only that reward it's given.
Say you're given the Uchiha bloodline as a reward or a jutsu scroll for kage bunshin, it won't give you chakra or the chakra circulatory system, only that reward so it's useless unless you aquire chakra or find another way to use said reward.
- the reward rolled can't be a system. Not even system functions like inventory or status individually can be got as a reward.
**You can however get a status plate like the protagonists of certain animes that land in another world either by themselves or with others (like a whole class) and are given status plates that apparently everyone in that world possess that allows them to see their classes (healers, assassin, hero, cleric etc.) and level along with sometimes their status. This status plate falls under magic tool categorization and is not a system function so if you're lucky, you can get one**
The rewards despite all the above restrictions are plentiful:
You have
- skills (carpentry, blacksmithing etc.)
- knowledge in it's entirety (whether physics or human body or insects or birds or animals or space or supernatural creatures or magic of a specific kind of of one particular technology ranging from a Nokia button phone to smart watch to portal guns from portal games or Rick and Morty etc. it's endless choices here)
- technology (similar to knowledge, you can get any technology ranging from my favorite, the indestructible Nokia phone to a holographic smart house or even spaceship etc.) <-- unless you get a pocket dimension of some kind big enough for hiding such, people will question where you got a spaceship from and may have it confiscated by the Government and/or whichever various organization(s) get to it first.
- abilities (both passive (always on) and active (abilities that can be turned on and off and consume more energy to use). Can range from poison resistance to flight to fireballs to waterbending to magic spells to quirks to pocket dimension access/creation etc.)
- passives (unlike abilities, there's only passive here. E.g. regeneration spacial awareness etc.)
- consumables (potions to food to poison to serums to devil fruits as well as even chakra fruits etc.)
- tools/equipment (stuff like weapons, armors, support stuff and staffs etc.)
It all depends on luck.
Note, the author should use a randomiser with the choices for rewards and the restrictions and write a story based off of that.
Only 13 rewards, no more. But can be less (because of previously discussed)
After 13th year reward, the system leaves for good with the ROB wishing success.