Seriously, this is going to be one long--I don't want to use the term wankfest, but that's probably the best word for it--okay, wankfest about The Elder Scrolls IV: Oblivion. Anyway, so I can quit boring Dempsey to tears over my constant talking about it, I decided to just make a massive blog post expressing my deep and everlasting love of the greatest game on earth. Feel free to stop reading now.
The developers made the game super easy to mod. Simply install the mod in the Data directory, go into the menu option and check the box next to the mod. Done! If you decide later you don't like it, go back and uncheck it. Done! That simple.
Unless you're like me and the many other mod-addicted gamers who run dozens or more mods (most I ever heard about is 270. They had to merge some to get around the 255 mod limit). For one, you have to worry about load order, and the default mod option lists them alphabetically. So you can use the Oblivion Mod Manager, a user made program, which does many things, not least of which is letting you set your mod order.
Then theres Wrye Bash. I don't know a lot of Bash other than to follow the instructions for the mods that use it. The same for the Oblivion Script Extender, which is another program that allows mod-makers to add to what Oblivion can do. You don't have to know a whole lot about these two to run your game. The most important thing to know is that if you use a mod that uses the OBSE, you have to run your game through it to get them to work. (Easy enough; just set up a shortcut on your desktop that kicks off the OBSE version of your game.)
See, a lot of the mods that have come out do things the base game doesn't do. New animations, new functionality entirely. I have a mod that adds, among other things, a lute animation to the game and lets you play the lute to increase a character's disposition toward you and even earn money.
So, what do I have my game doing?
Well, I'm running the biggest convergence of overhaul mods: FCOM. Overhaul mods are just what they sound like. They overhaul a vast majority of the game. For example, Oscuro's Oblivion Overhaul (the "O" in FCOM), in simplest terms, overhauls every aspect of gameplay. In default Oblivion, the game world levels with you. That means you can go anywhere in the world and not worry about running into something too overpowered. OOO changes that. Now everything is leveled, though somewhat loosely. You'll spend a lot of your lower character levels very close to the Imperial City, the large capital city in the center of the game world. An OOO world is harder, much harder, than vanilla Oblivion (unmodded Oblivion).
Then there's Martigen's Monster Mod (the "M"). It adds over 160 new monsters, quite a few of which are completely new meshes. (Think of a mesh as the skeleton of a creature.) Foxes, bats, rabbits, and more are part of MMM. You can set undead to have a chance to rise again once you've killed them, which makes dungeon crawling extra scary.
I also have Francesco's (the "F"). It adds hundreds of new objects, some new monsters, various other changes. The only part of FCOM I don't have is Warcry (the "C". Yes, I know.)
OK, that's the largest major change. So what else? Well, there's Supreme Magicka and L.A.M.E. Both are magic overhauls. Both make magic more useful by adding dozens of new spells, increasing the timer on many other spells, fixing some spells that were broken either as too exploitable or useless.
I have some smaller mods that do less but are nonetheless very important. For example, Harvest [Flora], which is part of OOO, fixes the problem in vanilla Oblivion where harvest plants didn't change their image. In other words, it was impossible to tell if you'd harvested the plant, and you wasted a lot of time going back over areas. Now when I harvest, the image changes.
I have a mod that puts saddlebags onto my horse. I mean, when I'm dragging my weighted-down carcass out of a dungeon, loaded down with armor, weapons, potions, gold, gems, etc. it's nice to dump off some of the excess loot in case I get into a fight on the way back to town.
And finally, I have most of the major quest mods. These probably impress me the most. People created these massive quest lines, many of which are even better than almost every quest Bethsoft came up with. There's The Lost Spires, which promises about 15 hours of gameplay. I've bought games that didn't provide that much entertainment, and The Lost Spires is free. There's Blood & Mud, which completely changed the town of Bravil in addition to adding a massive questline. I have a questline I started, and I'm not even sure which one of those I installed it belongs to. All-in-all, I think the quests I've put on the game have added an extra 100 hours of play time to the game.
That's just the tip of the iceberg. At last count, I have 97 .esp or .esm files. Many of them require each other to work, so I don't actually have that many mods installed, but it's still probably 75 unique changes to the game.
It may seem strange to label a game "greatest ever" when I've changed it so much it barely resembles itself. But that's exactly why it's the greatest. Instead of saying, "This would be a great game if only it would [insert change here]," I can say, "You know, I'd like it if I could do [X]. I wonder if that's possible." There's a decent chance it is.
I never understand the people who say, "I started playing Oblivion and got bored when I realized [some aspect of the game that I've never dealt with because of my mods]." And all I can think of is, "So why didn't you fix it?"