UPDATE 5 (31.05.2022):
- AOB script instead pointer+Lua timer for swing speed multiplier, some minor tweaks,
- included customized hybrid of "Reduced Backwards Running Speed Optimised" by Martigen and "No Backward Running" Ely Soto (Tornnight),
- added more speed variants of mod (x1.25, x1.5, x1.75 and previously seen x2.0),
- made special mod variants for "Melee Combat Additions" by Legion,

Goal is to make melee combat more intense and challenging.

Changes:

Standalone version:

- all enemies attacks and acts *2x faster,
- monsters moves *2x faster, NPCs only slightly faster,
- new dodging-dash system with "pseudo" i-frames for player character, block-dash possible too,
>by "pseudo" i-frames I meant that - when dodge is timed correctly (we are invicible 110 miliseconds after keypress) we take no damage, even from ranged weapon or spell, but still can get stunlocked or recoiled. It works like that because I couldn't find any trick with Cheat Engine to make player character totally invulnerable (no collisions+no damage),
- player attacks 1.2x faster,
- some actions of player are *2x faster, like vanilla rolls/flips - they became pretty usefull finally,
- backward running is removed, player will slowly walk backwards instead, no more kiting - block and dodge instead,
- 50% speed penalty triggered only when player is moving - to reduce kiting and silly supersonic moving speeds in all directions,
- player can't toggle walking because it's messing up dashing speeds and distance, it is blocked by script which auto enable running mode and disables toggle walk key afterwards,

For Legion's Melee Combat Additions which already has superior dodging system I've only included:

- all enemies attacks and acts *2x faster,
- monsters moves *2x faster, NPCs only slightly faster,
- player attacks 1.2x faster,
- some actions of player are *2x faster - MCA dash/roll too,
- backward running is removed, player will slowly walk backwards instead,
- 50% speed penalty triggered only when player is moving,

*multiplier value depends on which version is used - x2.0, x1.75, x1.5 or x1.25

Requirements:

Official Oblivion Patch v1.2.0416
http://en.uesp.net/wiki/Oblivion:Patch

OBSE (Oblivion Script Extender) latest version (0021 now)
http://www.nexusmods.com/oblivion/mods/37952/?

Only those things if we talk about Oblivion files - and they are required to Cheat Engine scripts and adresses works correctly.

Cheat Engine software (6.6 minimum)
http://www.cheatengine.org/downloads.php

AutoHotkey
https://autohotkey.com/download/


HowTo:

Standalone:

1. Copy "Data" folder to Your game directory, enable "ReducedBackwardsRunningSpeed" in Your desired mod manager,
2. Download and install Cheat Engine and AutoHotkey external software,
3. Copy "_Obek.ahk", "Obek.ahk" and "Obek.ct" from chosen speed variant folder to "C:\". Just "C:\". No subfolders. Now You can create shortcut of "_Obek.ahk" file and move it to desktop, etc. anywhere,
4. Launch "_Obek.ahk" file before launching game, press X to launch unactivated Cheat Table and AutoHotkey script,
5. Launch game,
6. Go to controls options, remap those keyboard commands buttons (MUST BE DONE):
- "Sneak" to Q,
- "Run" to L-Shift (probably set by default)
7. Load Your save or start new game, doesn't matter - but You need to be in game world - playing Your character, new game not required,
8. Press "\" keyboard key - it is hotkey to activate mod,
9. Done. If You are using mod for first time re-equip Your weapon to get new weapon speed multiplier and if You save the game You don't need to re-equip weapon again - game stores latest speed modifiers in save files,
Press left Shift button to dodge in any direction. You can dodge during block too.


For Legion's Melee Combat Additions:

1. Copy "Data" folder to Your game directory, enable "ReducedBackwardsRunningSpeed" in Your desired mod manager,
2. Download and install Cheat Engine and AutoHotkey external software,
3. Move "Obek.ct" from chosen speed variant folder anywhere,
4. Launch "Obek.ct" file before launching game,
5. Launch game,
6. Load Your save or start new game, doesn't matter - but You need to be in game world - playing Your character, new game not required,
7. Press "\" keyboard key - it is hotkey to activate mod,
8. Done. If You are using mod for first time re-equip Your weapon to get new weapon speed multiplier and if You save the game You don't need to re-equip weapon again - game stores latest speed modifiers in save files,

Compatibility:

Compatible with any modification that:
- doesn't modify Oblivion .exe or basic .dll files

Incompatible with:
- backward running related mods,

How does it even work?

Attack speeds in x2.0 example:
It works like that:
>First, whole game is speedhacked x2 - whole world, time, npcs, monsters and hero, everything except soundtrack and sound effects is 2x faster...
>Second, there is AOB script in Cheat Engine, which multiply player swing speed value - for example, if weapon speed value is 1.0
(longsword weapon type, bare fists or bow) script multiply it x0.6. Why 0.6? Mod makes player attacks 1.2x faster right? So:

1.0/2=0.5 -> /2 because whole game is speedhacked x2, so 0.5 will be default vanilla attack speed after speedhacking,
0.5x1.2=0.6 -> x1.2 because we want to have player attacking 1.2 faster, simple math here,

Speedhack related stuff:
Because speedhacking x2 some other worth noting things got 2x faster/shorter too, not only attack speeds of enemies (both NPCs and monsters):
- monsters moves 2x faster, NPCs use different movement formula,
- reaction time of enemies - 2x shorter delay between actions, block durations, etc.
- enemies and player raises block, starts swinging, etc. 2x faster too,
- spellcasting - couldn't find casting speed values, so sadly, both player and NPCs cast spells 2x faster,
- missiles, like arrows or spells flies 2x faster,
- duration of effects, buffs, debuffs, 2x shorter,
- knockdown, paralyze, recoil, stunlock etc. duration 2x shorter,
- acrobatics dodge rolls/backfilps, MCA dash/roll 2x faster,
- talking speed during conversations x2 faster too - sadly, that brings desync between dialogue playback and lip movement, no idea how to fix it,
- lockpick minigame 2x faster - it is really challenging now, go try the chest near Imperial City Arena xd (very hard lock type early),
- magicka and stamina regenerates 2x faster,
- most of player and enemies animations 2x faster too, looks comical sometimes, but melee is the focus of this mod, I just don't care,
- game time goes 2x faster, game messages too, sleep slider 2x faster too,

New dodging system:
Combination of AutoHotkey macros which enables sneak mode for certain amount of time and hotkeys in Cheat Engine which alters sneak speed multiplier for certain amount of time too + activates godmode for certain amount of time too.
Really simple workaround to not get involved in scripts.
Still Legion's MCA mod with superior dodging system is recommended.  

Reccomended Mods:

Maskar's Oblivion Overhaul (best overhaul imo)
http://www.nexusmods.com/oblivion/mods/42780/?

Legion's Melee Combat Additions (best combat mechanics mod imo)
https://www.nexusmods.com/oblivion/mods/49939?

DarNified UI
http://www.nexusmods.com/oblivion/mods/10763/?

Unofficial Oblivion Patches
http://www.nexusmods.com/oblivion/mods/5296/?
http://www.nexusmods.com/oblivion/mods/10739/?
http://www.nexusmods.com/oblivion/mods/9969/?

EngineBugFixes
https://www.nexusmods.com/oblivion/mods/47085/?

NVAC - New Vegas Anti Crash
https://www.nexusmods.com/newvegas/mods/53635/?

DDD ENB - Cinematic Fantasia (best ENB imo)
https://www.nexusmods.com/oblivion/mods/45269

FCOM or MMM not reccomended (because enemies lying on ground in middle of combat because fatigue and other nonsenses in game world)

Example videos:

older and before backward running nerf got included but explains a bit more:


***I just forgot to mention that huge carry weight boost is enabled by default - if You want to disable it edit Your chosen .ct file with any text editor, find, delete those 3 lines:

  mr3 = getAddressList().getMemoryRecordByDescription("TOTAL WEIGTH")
  mr3.Active = true
  mr3.Value = 100

and just save the file