To add to Pantsless Bob's excellent chronological writeup above, City of Heroes has a number of additional interesting features.

Characters ("toons") are able along the way to become more distinguishable from each other in a number of ways.

At level 15 and 25, a character can choose a title. There is a common pool for level 15, and an origin-specific set for level 25. You get the choice of adding "The" before your name and title as well.

Costume and appearance
At level 20 and 30, your character can visit the City Representative in Atlas Park to get a very special mission arc. At level 20, it is an arc to retrace the history of one of the greatest (posthumous) heroes, Hero 1, starting out by talking to those people who knew him, culminating in a fight to protect a time capsule he and his team have made. Your reward for this is the ability to wear a CAPE! These come in long, short and insect wing varieties, and make a superhero REALLY spiffy! These can have a huge variety of patterns on them, making the choices for your look to be almost endless.

At level 30, you again are set a story arc, the successful resolution of which results in the ability to select an AURA. There are far more initial choices of aura, but they are un-customisable. Being surrounded by sparkles, mist, a glow, having perpetually glowing hands, glowing eyes - all add to the mystique of your character. The biggest downside to an aura is that it is quite graphically intense, so that most players with low-spec PCs turn them off.

Costume slots
At levels 20, 30 and 40, you can do a story arc for Serge, the owner of the superhero tailor "Icon" in Steel Canyon. Generally fighting off the local ruffians, your reward is a new costume slot. By customising it (a VERY expensive process) you can easily switch between up to 4 costumes (5, if you see Supergroups, below).

Body Scaling
With the release of Issue 4, players have been able to scale their body shapes to a degree. Fat, thin, big-hipped, big-boobed, long or stumpy legged, big/small heads, you name it, you can do it. The three body types (Male, Female and Huge) all have aspects that make them even MORE customisable.

One enhancement type was left out above - Hamidon enhancements. Only awared on defeat of that super villain, these enhancements count not only as Single Origin (+33%) enhancements, but apply that bonus to TWO aspects of the skill - +Accuracy and +Defence, for example.

Badges are one of the coolest aspects in the game. They come in a variety of categories:

  • Exploration: The most easily obtained, you simply have to be near a badge marker in the world to be awarded them. They have no value (other than bragging rights) and varied names, but add a lot of "flavour" to the game, as they often outline big events, famous character history or commentary about a particular area.
  • History: Around Paragon City are plaques which follow a particular theme - be it the formation of superhero governmental support, to following the life of a hero or villain, to the description of a zone and it's evolution. If you collect all of the plaques in the group, usually spread across many zones, you are awarded a named History badge, with a synopsis of the story you have uncovered. Plaques are sometimes notoriously difficult to find (up on a wall down a small alley) and generally only found with an online (cheating) guide. Some of the awarded badges are required for Accolades (see below).
  • Achievements: Awarded for "doing" stuff in the game. Examples include killing 100 bosses of particular mobs, survive a fight in a nuclear reactor, complete a taskforce (see below), being killed/restrained often enough, earning Influence or having a sidekick for a long enough time... Achievements are the TRUE indication of what a hero has done. Some are quite difficult to get straight away, but you can always go back and complete them later, say when the enemies they refer to are far weaker than you.
  • Accolades: The most difficult of badges to get, they involve the obtainment of multiple Exploration, History and Achievement badges. However, these badges actually have a REWARD attached to them - be it a small permanent increase in Endurance or Hit Points, a special attack that can only be executed once every 25 minutes, or a VERY temporary boost to your attributes every half hour, Accolades are to be prized.
Taskforces (TFs) are story arcs that you receive from NPC's in Paragon City. Requiring a minimum number of members on a team, these often gruelling series of missions are a true test of a heroes skills, patience and determination. Often set to be continuously difficult, taskforces can take upwards of 5 hours to complete. To balance this, you can log off and not lose your place in a TF. There is often a reward or rewards - unique badges most of the time, but also Enhancements, all the way to a coveted respec (see below).

Not everyone gets their character quite right the first time. The game also changes the required tactics along the way (great for playability!). Occasionally (usually with the release of an Issue) different aspects of the game balance are changed. Whatever the reason, one of the most prized things in the game is a respec - a full respecification of your skills, enhancement slots and enhancements. To get one of these rare things, you either have to a) wait until a major Issue release, b) wait until the developers are feeling generous (unlikely to ever happen again) or c) earn it!

To earn a respec, you have to form a taskforce (see above) to defend one of Paragon City's most valuable (and thus coveted) buildings, the Terra Volta nuclear reactor. A gruelling task that is set to always be 2 levels above the HIGHEST LEVEL character in your TF, it is a challenge for anyone. With unique levels and a battle royale at the end (think waves of enemies!), it is a truly satisfying feeling to complete successfully.

Once you've actually GOT a respec, you cannot change your primary or secondary power pools, but everything else is fair game. You can select the powers (from the same base power pools) but enhancement slots, tertiary powerpools and even enhancements are released from their locked-in status to be re-allocated! If you respec different powers that use different enhancements, or simply don't want them any more, you have the option of automatically selling the true value of the enhancements.

Respecs are great to drop a power that, looking back on it, just wasn't that great. It is also great to re-allocate enhancement slots, if you accidentally over- or under-allocated slots to. With a theoretical maximum number of respecs (about 6) these non-badged rewards are nothing to be sneezed at.

New primary and secondary power sets
With the release of Issue 5, two new power sets have been released - Archery and Sonics. Given to Blasters, Defenders and Controllers, these new sets give some of the most underused archetypes (Blasters), or most OVERUSED powersets (Defender with Radiation/Empathy powers) some choice to encourage experimentation. Having not played them enough, I'll leave the powers as an exercise for the reader.

New Zones, new monsters, new excitement - oh my!
Issue 5 also release a new Zone, something that has been done before. "Croatoa" is an enchanted forested area, filled with new monsters (The Cabal, Fir Bolg, Red Caps and Tuatha de Danaan) and with new possibilities. Connected to the Paragon Transport Authority Green line monorail, it is for levels 25-35.

Not Oasis, a Supergroup (SG) is a collection of heroes which is meant to be a regular "team". Anyone from Level 10 and up can register an SG for free at the Town Hall at Atlas Park, and with it, you get some more information, a message of the day, and an SG-only costume. More like a colour change, the primary and secondary colours of any item of clothing can be changed to one of two SG colours. SGs can form "Coalitions", basically joining two SGs together, allowing large communities to form.

Arena battles
Fairly new is the concept of PvP superhero battles. 3 arenas have been built in Galaxy City, Talos Island and Steel Canyon, allowing superheroes to pit themselves against each other! Some make for exciting battles, and spectators can watch, but the worst part about the arena is the fact that it hasn't been around for as long as it should. If implemented early, a whole arena culture could have developed, but despite being implemented well, even months after it's release, it has a feeling of being "tacked on".

As you can see, City of Heroes is a HUGE game. It is going to continue as a successful MMORPG well into the future. With City of Villains on pre-order as of September 2005, the future looks bright for the superhero world!

Remember: Statesman says: Superheroes don't do Superdyne!

Damodred says: Nice wu; I'd add that Ish 5 also added several fantastic mission tweaks.
Right he is! Issue 5 introduced escort, protection and a variety of other mission styles. These add on top of the "defeat all XXX in base", "find XX captives", "disarm X bomb(s)" missions.