Post: #1

Ported from RunUO forums, credits to nerun.

24.09.1997 - [1.0.0 to 1.25.35] - Ultima Online (original game)

01.10.1998 - [1.25.35b to 1.26.4j] - The Second Age (+ Lost Lands)

03.04.2000 - [2.0.0 to 2.0.9a] - Renaissance (divison Felucca / Trammel)

07.03.2001 - [3.0.0 to 3.0.7a] - Third Dawn (3D client, +Ilshenar)

24.02.2002 - [3.0.7b to 3.0.8r] - Lord Blackthorn's Revenge (+30 mobiles by Todd McFarlane)

11.02.2003 - [3.0.8z to 4.0.4b2] - Age of Shadows (+Malas, new classes Paladins / Necromancers, custom houses, 5 resistances, item insurance, weapon abilities)

02.11.2004 - [4.0.5a to 4.0.11c] - Samurai Empire (Tokuno, new classes Samurai / Ninja)

30.08.2005 - [4.0.11d to 5.0.9.1] - Mondain's Legacy (new race Elves, spellweaving, new dungeons)

27.06.2007 - [6.0.0.0 to 6.0.14.3] - Kingdom's Reborn (new client, new graphics, essentially new game)

08.09.2009 - [6.0.14.4 to 7.0.8.2] - Stygian Abyss (new client, new race Gargoyles, new places, removed support for UO:KR)

12.10.2010 - [>=7.0.9.0] - High Seas (sea stuff, new ships, sea markets, pirates etc)

Magincia Changes:
Old Magincia [Client <= 6.0.3.1]
Magincia Ruins [6.0.4.0 <= Client <= 7.0.13.0]
New Magincia [Client >= 7.0.13.1]

Notes by me:
Clients after 7.0.24.0 > Use new file format .uop, not more .mul, beware of this if you want to add objects or new animations, it may be more difficult or incompatible.

For a server pre .UOP i recommend the 7.0.20.0 client, best stable High Seas version.

For a server Stygian Abyss i recommend the 7.0.8.2 client, best stable Stygian Abyss version.

For a server old school, i recommend 4.0.11c or 2.0.3 client.

Regards!