Apple keeps a hard line on mature content, so a whole category of 18+ anime and fantasy games never makes it to the App Store. These are mostly gacha RPGs and strategy titles with adult art styles and mature storylines — popular worldwide, but blocked on iOS by review policy rather than by anything technical. Below are the most-searched ones and how to install them on iPhone without a jailbreak.
These titles are intended for adults only (18+). Install at your own discretion and keep them off shared or family devices.

Busty Fantasy Burst
An anime-style gacha RPG built around collecting characters and clearing turn-based battles. The draw is its mature art direction and character roster, which is exactly what keeps it off the App Store. It is the single most-searched title in this category.
Chronicle of Immortals
A fantasy idle RPG with a cultivation theme — recruit heroes, grow your power, and progress largely on autopilot. The mature character art and storyline put it in the 18+ bracket. It is a good pick if you prefer steady progression over constant micromanagement.
Daraku Gear
An action gacha with a stylized anime look and a heavier combat focus than most idle titles. You collect and upgrade fighters and take them through stage-based battles. Its mature presentation is the reason it lives outside the App Store.
Everlusting Life
An auto-chess / auto-battler where you build a board of anime characters and let positioning and synergies decide the fight. It rewards planning more than reflexes, so it suits shorter sessions. The mature roster is what keeps it in the 18+ category.
Alliance Sages
A fantasy strategy RPG that mixes hero collection with squad-based tactics. You assemble a roster, level it up, and take on both story content and other players. The mature anime art style is why it never passed App Store review.
Sugar Conflict X
A gacha strategy title with a bright anime style and a mix of collection and battle modes. You pull characters, build a team, and grind out upgrades between fights. Its mature theme places it firmly in the adults-only group.
Thrones and Beauties
A kingdom-building strategy game set in a historical fantasy world, with city growth, army management, and alliance play. The mature character art is the part Apple will not approve. It is the most strategy-heavy entry on this list.

How to install these games without a jailbreak
No computer and no jailbreak required. Open any app page above on your iPhone, tap GET, and install from Safari. The first time you add your device, most iPhones are ready within a day; some take up to three days while Apple processes the device on the signing certificate — normal, and it only happens once. After that, installs are instant.

Why the builds.io builds beat random IPA sites
Free IPA mirrors revoke on a schedule — you install today and a few days later the certificate dies and your save will not open. These builds stay signed, so your progress stays put without re-sideloading after every revoke. No cable, no AltServer on a laptop, no weekly refresh.