As expected, there are numerous similarities between City of Heroes and City of Villains -- in many instances this is a good thing, but in some ways the game is disappointing. To their credit, though, Cryptic did a marvelous job utilizing the same tools to create a different effect.
For example, most of the graphics and animations in CoV are the same as the graphics and animations in CoH. But with the clever usage of lighting, placement, and a few new additions, the Rogue Isles are militaristic instead of pristine.
Skills, at first glance, are a major disappointment; there are very few new powersets, and most of the new ones belong to the Masterminds. Once I started to play, though, I realized how different the CoV Archetypes are from their CoH counterparts; the mix of powersets creates truly different characters that require an entirely different game play style. Corrupters don't play like Blasters, but they also don't play like Controllers; even Stalkers are a far cry from their Scrapper brethren.
Unfortunately, there is still a lot of balance work to be done with the CoV classes. Some archetypes are just way more powerful than another. For example, a Mastermind with six robots or ninjas can clear an entire mission on the highest difficulty setting, relentless, while a Corrupter might have a hard time on the easiest setting, villainous.
Many of the missions seem similar to those you might complete in CoH, just with a different story to go with them (i.e. instead of disarming a bomb, you arm it!). The exceptions to this are the kidnapping and bank robbing missions, both of which are somewhat painful. In the kidnapping missions, I had some problems getting my victims to follow me without getting stuck. The bank robbing missions are nearly impossible for Corrupters or other delicate classes.
One cool new mission-related addition to City of Villains is the newspaper missions. Instead of being confined to contacts, villains can do randomly generated missions from the newspaper. You get a choice of three different missions, which means more choice in what kind of mission you run -- hate kidnappings? No problem; just volunteer to steal some top-secret documents instead. Doing newspaper missions earns you brownie points with the broker for your zone. The broker can then introduce you to new contacts so you can run storyline missions if so desired.
While in the missions or on the streets, many of the NPCs you fight are the same ones found in CoH; just this time, instead of trying to vanquish the evil of the Circle of Thorns or Council, you are trying to prove that you're more evil.
Now for the new stuff. One of the most prominent new features of City of Villains is the base building system. The only system that you can really compare base building to is costume creation. There are several hundred decorative items to be placed anywhere you want in bases. Ceiling and floor tiles can be raised or lowered to create platforms or small rooms. Even the lighting is entirely customizable, both in intensity and color.
Bases also serve many functional purposes. Players can build different useful objects in different rooms of the base: Reclaimators so that supergroup members can resurrect to the base rather than the hospital; Telepads to teleport from the base to any zone that the supergroup has fully explored; Autodocs to buy inspirations; weapon and defense systems to protect Items of Power; and many crafting tables to deal with salvage. Some of these objects require salvage to build as well as prestige.
Salvage is also a new feature of the game. Salvage is obtained by killing NPCs and can be refined into crafting components on crafting tables in bases, and then used to help create the above listed objects.
Bases also give players the ability to hold Items of Power, special objects that give supergroup wide buffs, either by raiding other bases or by completing the Cathedral of Pain Trial given by the Mission Computer. The buffs from these items are very useful, but also come with a price... to keep their Items of Power, supergroups have to defend their base. Base items can also become damaged, making Item-hoarding an expensive task.
Also new in CoV are the PvP zones. In the first zone, Bloody Bay, all players are made level 25, whether they are really level 20 or level 50. In this zone it's heroes versus villains and is fairly straightforward; the main plus of this zone is a quest to collect meteor samples to obtain a powerful summon. The next zone, Siren's Call, automatically makes all players level 30. In this zone is a battle over hotspots; every few minutes a hotspot will pop up where NPCs and PCs fight over the area. While in Siren's Call you can build up your bounty by killing specific enemies to take their bounty, then trade it in for rewards. The problem is, if you're killed, your killer gets your entire bounty! The last PvP zone, Warburg, is a free for all. In this zone you can do a special mission to receive another powerful temporary power.
In all of these zones you can run missions that either boost their side's abilities or hinder the other side, such as damage or damage resistance buffs or debuffs. Players can also come to these zones just for PvE. This can be beneficial as there are more opportunities to obtain salvage drops from the numerous bosses and lieutenants in the PvP zones and you can get salvage from running the missions in the zone.
One of the big draws for City of Villains is that casual and hardcore friends can play at their own speed and still hang out and run missions together. This is made possible by the lackey system (the equivalent to City of Heroes' sidekick system), which allows lower level players to lackey to a higher level friend, or lets higher levels malefactor down to the level of their friend (the former being the more popular and profitable option). While in range of their partners, lackeys have the fighting ability of a character one level lower... i.e. if a 5th level character lackeys to a 20th level character, the 5th level character will fight like an 19th level character. While the lackeys aren't as proficient as a normal 19th level character -- they have less skills, their enhancements aren't upgraded, etc -- they are able to contribute to the mission and receive rewards of experience and enhancements suitable to their level, as well as experience and salvage. Malefactors are lowered to the level of their partners, losing all their higher level skills though keeping their enhancements and enhancement slots. While partnered, malefactors don't get experience, but they do get extra infamy and can work off debt.