Obsidian Conflict is a cooperative modification created for Half-Life 2. It is a community based mod with focus on fun, cooperative, and physics-related puzzles. The mod has an open story, but is still set in the Half-Life 2 universe.

Below is the complete change log. But beware, it's almost endless!

[Add]'renderdist' keyvalue for all entitys that are able to use holograms (it specifies how far away the effect begins)
[Add]'stopsounds' which is the same ConCommand as 'stopsound' but without the need for cheats being enabled
[Add]Devs & Donators having the Custom Color set on Chat, Scoreboard, TargetID & Deathnotice
[Add]Command 'rcon_say' which is mostly used by HLSW to display the right name instead of just Console (name must match one of those in cfg/allowed_admin_names.cfg)
[Add]Per Map Particle Loading via Manifest file in the following format: particles/particles_.txt (the format inside of the file is the same as for the default manifest file also in that directory)
[Add]'bot_add' ConCommand (pretty much the same as 'bot')
[Add]'[Beta]' GameModeTag while being in Beta Development & '[L]' GameModeTag when running an Listen Server
[Add]Usage Description for ConCommand 'playgamesound' when no Argument is given
[Add]ConVar 'cl_restrict_server_commands' ( which was removed by valve ) to prevent server executing commands on the client
[Add]Addon System (loads every folder as game folder under add-ons that contain a info.txt with the exception for ep2, episodic, lostcoast, css, dod and hl1 which only get loaded when the correspondenting mount is enabled)
[Add]ConVar 'motdurl' any url used with this ConVar (change it's value to 'none' or simply '' to use the motdfile ConVar) will automatcally get's the current version string passed trough (PHP: $_GET["version"]) which makes the MOTD more dynamic, feel free to request more...
[Add]ConVar 'sk_bigmomma_meelee_range' which specifies the distance in units where BigMomma will try to run after you to meelee attack you
[Add]New Spawnflag on 'point_viewcontrol' which gives the ability to hid the affected players hud for clear view
[Add]'server_default.cfg' and 'listenserver_default.cfg' to provide basics for a successful server setup
[Change]Made ConVar 'r_rainwidth' a non-Cheat (request by Tysn for harvest)
[Change]Dedicated Server Console Messages are now Red Colored
[Change]Join/Leave Messages are now Green Colored
[Change]Namechange Messages are now Orange Colored
[Change]Teamchange Messages are now Brown Colored
[Change]Tickrate has been limited to 66 because any higher can cause problems
[Change]Handling for SteamID. (Now OC shouldn't be affected by an SteamID change anymore)
[Change]completly disabled 'ch_createapc' for now
[Change]Removed Lives from saving over Transistations as it's causing problems
[Change]Removed Coloring of the Scope for the Sniper
[Change]Map Overview will now automatically turn on when it's available
[Change]ConVar 'sv_allowgaussjump' & 'sv_tauplayerradiusdmg' is now a non-cheat ConVar
[Change]Entity 'item_ammo_crate' now uses proper models for Crossbow Bolts, Combine Balls and 357 Ammo
[Change]ConCommand 'fov' is now a non-cheat command and locked to 75-90
[Fix]'npc_apcdriver' spawnflags 'No Rocket Attacks' & 'No Gun Attacks' being useless
[Fix]Player MuzzleFlash turning on when Assassin or Barney started shooting, which was caused by an Angle fix for the MuzzleFlash added in 1.34
[Fix]Local Player being visible in 'point_viewcontrol' even when the flag 'Player Invisible' was set
[Fix]Rare Crash in Ammo Hud caused by Scripted Weapons
[Fix]LivesCounter Panel not hiding when the Player is dead under some circumstances
[Fix]Rare Crash caused by Waypoints
[Fix]Clients able to use ConCommands 'rr_reloadresponsesystems' & 'sv_soundlist_dump' & 'sv_soundemitter_flush' & 'sv_soundemitter_filecheck' & 'sv_findsoundname' to lag/crash servers
[Fix](Team)Score can't go negative when using 'game_score' even with the Negative Flag set
[Fix]Lives going negative in some circumstances
[Fix]Calling FireUser* required a String Argument even tough Hammer didn't say so
[Fix]Input 'Kill' and 'KillHierarchy' & ConCommand 'ent_remove_all' being able to remove players which caused problems and in some cases a crash
[Fix]ConCommand 'ent_setname' not being able to handle special identifiers like '!self'
[Fix]Crash caused by entity 'game_ui' when a player that is affected by it disconnects
[Fix]'npc_antlion' and 'npc_antlionworker' not being able to burn
[Fix]'npc_combine_camera' not firing 'OnDeath' & 'OnLostEnemy' & 'OnLostEnemyLOS' & 'OnLostPlayer' & 'OnLostPlayer' Output
[Fix]Rare Crash caused by 'npc_mortarsynth'
[Fix]Entity 'logic_measure_movement's Input 'SetMeasureTarget' & 'SetMeasureReference' & 'SetTarget' & 'SetTargetReference' not handling '!activator' & '!caller'
[Fix]'prop_vehicle_jeep' turning into an 'prop_vehicle_jeep_episodic' even episode two isn't enabled
[Fix]'ch_createjalopy' being usable when cheats are enabled even tough EP2 isn't enabled causing the Server to crash
[Fix]'showtriggers_toggle' being usable without cheats (a leftover from some old beta testing)
[Fix]'point_viewcontrol' not turning off on the end of a map which causes render errors
[Fix]'trigger_playermovement' not properly removing forced duck from player when leaving the trigger
[Fix]Player getting negative Score even 'sv_allownegativescore' is set to 0
[Fix]Entity 'func_tank' and subclasses spamming the console with 'Ammo Remaining' Messages
[Fix]Entity 'func_tankairboatgun' & 'func_tankphyscannister' not firing Output 'OnFire'
[Fix]Airboat 'prop_vehicle_airboat' causing a crash when calling for example the 'EndGame' Input of a 'game_end' while a player drives it
[Fix]'func_precipitation' not showing up on monitors ( no reflective glass support yet )
[Fix]OC Map Particle Loading not working ( Particles {} in _modify.txt & _particles.txt )
[Fix]Weapon 'weapon_sniperrifle' not zooming out while reloading (thus not zooming back in after reload too)
[Fix]Map Overview not being at the right position (was conflicting with the score panel)
[Fix]MOTD and Map Briefing showing up on Background and Commentary Maps
[Fix]Entity 'trigger_serverragdoll' not respecting Filter Flags
[Fix]BigMomma spit colliding with brush trigger
[Fix]Cleaned BigMomma's AI a bit to let it use Spit, Meelee and Headcrab spawn use more smoothly (it isn't perfect but better then before)
[Fix]Bigmomma not fading away when dead
[Fix]Alien Grunt trying to kill Enemy Hornets
[Fix]NPC 'monster_alien_controller' hurting other alien controller with their attack which are in the same team
[Fix]physics objects that are stored into the inventory now also force their childs to be nodraw (fixes things like env_sprite glowing at the players position)
[Fix]Rare Crash on client while processing entity data
[Fix]Airboat Gun not using the right Ammo HUD
[Fix]Player being able to block 'item_ammo_crate' Entitys by constantly pressing USE at it
Maps
[Add]ep2_oc_broken_escape_02a added/updated
[Add]ep2_oc_broken_escape_02b added
[Add]ep2_oc_broken_escape_02c added
[Add]oc_cardwar added
[Add]oc_starship_troopers added
[Add]oc_wildfire added
[Add]coop_zelda01_b added
[Add]oc_zelda02_g added
[Add]oc_newgappi_g added
[Add]oc_return_c17_01 added
[Add]oc_return_c17_02 added
[Add]oc_return_c17_03 added
[Add]oc_return_c17_04 added
[Add]oc_return_c17_05 added
[Add]oc_return_c17_06a added
[Add]de_dust mapadds added
[Update]ep1_oc_broken_escape_01
Significantly shortened the trainride
Added background buildings to the trainride
Various optimizing
Tweaked difficulty a bit
Reworked some npc spawning
Graphically improved some areas
Transition to ep2_oc_broken_escape_2a added
Reworked the HDR lighting
Compiled lighting with -StaticPropPolys -StaticPropLighting -Final
Other minor changes
All content is now in the mod folder instead of the bsp file
[Update]oc_waking_dead
Reworked the fog, better atmosphere, much higher view distance
A lot of optimizing all over the map, hopefully no more vertex engine errors
Some model textures on brushes and displacements fixed
Some game breaking bugs and exploits fixed
CS:S weapons will now use the mod's weapon scripts instead of the old outdated ones which were embedded in the .bsp
Fixed some mistakes in weapon placing, resulting in wrong weapon behaviour like a shotgun-p90
Other minor changes and fixes
[Update]oc_lobby
Added a few more info posters
Compiled with HDR
Made The Alyxgun the default weapon on startup
[Update]oc_manor
No Longer requires Lost Coast to be mounted
Players now start with a cz52
[Update]oc_stitches
Players now start with a cz52
Many weapon pickups are now in the second map
Increased the number of enemies
The Lieutenant's guards are now armed with g36c's
[Update]oc_fireteam
Players now start with a smg1
An ammo crate of smg1 grenades is now located at the end of the first map, so games can't get deadlocked when fighting the strider
Added a few more enemies
Added various weapon pickups
Placed a respawning rocket launcher in the final section of the second map to prevent deadlocks
Included worfox's map origin spawn fix for the second map
[Update]oc_courier
No Longer requires Lost Coast to be mounted
Players now start with a spas12
Shotgun ammo crates are now at all spawnpoints
Some oicw's and g36c's are scattered around the map
Added more ambient sound
Music now plays during the defense finale
Fixed some of the game_texts displaying cut-off messages
Remove the now unnecessary shotgun ammo for sale from the merchants
[Update]oc_harvest
Fixed Juniper Texture
New farm upgrade: Drip Irrigation. Allows large numbers of crops to be watered easily
New farm upgrade: Greenhouse. Lets brown mushrooms be grown on the farm
Compiled with HDR
New rain sound
Added color correction effects when raining
New spa music
Added color correction effects to the spa
Made new Tree models and placed them around the map
Added birds to the forest, can be hunted for meat at $5 each
Updated pawnshop merchant weapon sales for bird hunting:
Crossbow: $50 Ammo $1
Magnum: $100 Ammo $3
Sniper Rifle: $150 Ammo $5
New farm upgrade: Smokehouse. Lets you marinate and smoke bird meat to turn it into jerky
Prevented Kitchen items from being thrown into the harvest bin
Lowered the cost of the portable produce teleporter from $950 to $750
Placed physics clips over the rock clusters to prevent people from throwing things behind them
New Grass Texture
Added mountains to the skybox
2D skybox changes for raining weather
New plant type: Tomato, costs $20 and continues growing indefinitly as long as it is watered
New plant type: Corn, costs $45 and continues growing indefinitly as long as it is watered
New farm upgrade: Fertilizer. Allows tomatoes and corn to be grown on the farm
Increased sale price of eggs from $15 to $20
Increased price of bullchicken feed from $15 to $20
Increased sale price of fried eggs from $20 to $25
Merged barn harvest bin system with the one outside. Next day profit from sold eggs now appears on the outside tables rather than inside the barn and therefore is affected by the farm upgrades.
Lowered the cost of bullchickens from $65 to $40
Increased sale price of banana cream pies from $45 to $50
New Kitchen Recipe: Salsa
New Kitchen Recipe: Guacamole
Fixed missing fencepost next to the harvest bin
New Farm Upgrade: Automatic Teller Machine. Allows cash to be stored and withdrawn
Rainbow now appears on clear days after rain
New after rain music
On days where there is a rainbow, there is now a very small chance that a pot O' gold can be found in the forest. It can be sold at the pawnshop for $90
Added hunting poster to the forest
New Hardware Store Item: Cookbook. Gives a list of recipes to use in the kitchen
New Farm Upgrade: Alarm Clock. A toggleable item that can be used to increase the length of days
Implemented an unplanted seed limit to prevent rich players from lagging/crashing the server by buying a ton of seeds
Added plant limits to reduce the risk of servers crashing
Size of antlion attacks are now based on the number of individual farm upgrades, rather than strictly off of the harvest limit upgrades
[Update]oc_kake updated to version l
[Update]oc_umizuri updated to version j
Misc Content
[Add]New model and sound for cash pickups
[Add]"CZ52" Custom Weapon
[Add]"mp5k" Custom Weapon
[Add]"ak5" Custom Weapon
[Add]"Remington 870" Custom Weapon
[Add]"HMG1" Custom Weapon
[Add]bucket positions list for custom weapons
[Add]Icon for the alyxgun rounds and a picture in the drop ammo menu
[Add]Manhack "ammo" icon
[Add]Grapple hook icon
[Add]Annabelle icon
[Add]Citizen suitcase icon
[Add]Citizen package icon
[Add]Oldmanharpoon icon
[Add]New GameIcon
[Add/Fix]Included some common NPC models to prevent "misaligned node" engine error caused by the dynamic mounting
[Add]Smg1 distance sounds
[Add]models for .357, crossbow and ar2 alt-fire ammo crates
[Add]Chinese Translations
[Add]new gamestartup song (Path of Borealis rock version by Alex23)
[Update]Made G36c NPC-usable, changed accuracy and fixed muzzleflash/ shell ejection as well as the world model not being held in the player's hands
[Update]CS:S weapon models updated with proper muzzleflashes and shell ejection
[Update]Spas12 now holds 10 rounds and has a new firing sound
[Update]Some mapadd updates for the campaign maps
[Update]Uzi animations and sounds updated
[Update]Updated Japanese translations
[Update]Made AR2 model 2-handed
[Change]Scout now uses .357 ammo instead of AR2
[Change]AK47 now uses AR2 ammo instead of custom ak47 ammo
[Change]Firerate of some CS:S weapons tweaked
[Change]xm1014 replaced with spas12 until auto-shotgun code is fixed
[Change]Tweaked some settings in skill.cfg
[Change]Raised gauss max charged damage
[Change]changed healer's empty sound
[Fix]Assassins pistol having a missing texture when running in HDR mode
[Fix]M3 now shoots at the correct speed