Welcome to the expansive and immersive world of "The Elder Scrolls," a landmark series in the role-playing game (RPG) genre developed by Bethesda Game Studios. Renowned for its rich lore, open-world exploration, and deep customizability, "The Elder Scrolls" has cemented its place in the hearts of gamers around the globe. The series allows players to embark on epic quests, delve into ancient dungeons, and forge their own destiny in a meticulously detailed fantasy universe.

All Characters and Levels of the Game:
"The Elder Scrolls" series is known for its wide array of characters, from noble heroes and cunning villains to enigmatic gods and fearsome beasts. Players can create and customize their own character, choosing from a variety of races, such as Nords, Khajiit, and Argonians, each with unique abilities and cultural backgrounds. The games do not have traditional levels but rather expansive regions to explore, each with its own set of quests, challenges, and storylines that adapt to the player's choices and actions.

What Attracts Users Most to the Game:
Players are attracted to "The Elder Scrolls" for its deep lore, vast open-world landscapes to explore, and the freedom to play in any style they choose. The ability to influence the world and its narrative through choices and actions is a central allure, allowing for a truly personalized gaming experience. Additionally, the intricate magic system, diverse character customization options, and dynamic combat mechanics offer endless entertainment and replayability.

Why It Is Popular:
"The Elder Scrolls" has gained immense popularity due to its detailed world-building, engaging storytelling, and groundbreaking freedom afforded to players. Its popularity is further bolstered by the strong modding community, which has extended the life and appeal of the games through countless user-created modifications that add new content, features, and improvements to the immersive experience.

When the Game Was Released and How Many Versions Are Currently Available:
The first game in the series, "The Elder Scrolls: Arena," was released in 1994. Over the years, the series has expanded to include major titles such as "The Elder Scrolls II: Daggerfall," "The Elder Scrolls III: Morrowind," "The Elder Scrolls IV: Oblivion," and "The Elder Scrolls V: Skyrim." As of my knowledge cutoff in 2023, there have also been several spin-offs and expansions, increasing the total number of games and versions available.

The Most Difficult Part of the Game:
The difficulty of "The Elder Scrolls" games can vary greatly depending on the chosen playstyle and difficulty settings. However, many players find the most difficult parts to be the strategic real-time combat with powerful bosses, the navigation through complex questlines with multiple outcomes, and managing the intricacies of character development and item crafting systems.

Strengths and Weaknesses of the Game:
A key strength of "The Elder Scrolls" series is its open-world design that encourages exploration and discovery. The games' strengths also lie in the sophisticated lore and well-crafted questlines. On the downside, the series has been critiqued for occasional bugs and AI inconsistencies, and some players find the combat less refined compared to more action-focused RPGs.

What Other Games Have Been Developed by the Same Developer:
Bethesda Game Studios, the developer behind "The Elder Scrolls" series, is also famous for creating the "Fallout" series, particularly the later entries such as "Fallout 3," "Fallout 4," and "Fallout 76." Other notable titles from the developer include "The Elder Scrolls Online" - an MMORPG set in the Elder Scrolls universe - and the upcoming highly-anticipated space RPG, "Starfield."