In the opening movie sequence, which seems highly influenced by The Lord of the Rings in both voice-over and cinematography, the Locusts have been sinking human cities. Jacinto is one of the last surviving places and in order to protect it, Alpha squad decide to take the fight to the Locusts. Throughout the game, the story-telling and visual design feels like there's a bigger war going on since you see more people fighting from humanity's side. Overall, the delivery feels much more cinematic; the whole game seems designed with an idea of epic proportions.
The core game-play remains identical to the original game. You are required to utilise cover in order to minimise damage, and pop out to shoot at your enemies. The 'Active Reload' feature remains intact, where you have the option of timing a button press for faster reload and extra damage. Mistiming means a long reload time, and not using it at all gives a standard reload.
There's still not a lot of story going on. There's one personal story of Dom looking for his missing wife, and there's some mentions of Marcus' father Adam, hinting that his story will be developed in the third instalment.
The graphics have been given a large overhaul. They still resemble the style in the original game, but feature a much higher level of detail and an increased amount of colour. This is a welcome change since one problem of the original was that it was so dull and grey, it was easy to mix up your own team mates with the enemy. Now it's much easier to tell them apart and everything looks really beautiful as you traverse the environments. You'll spend most of your time in underground caverns, but there's enough variety of locales throughout your battles.
When you get knocked down, your allies can now revive you. You have limited time before you fully die, but you can crawl to safety. This can also apply to the enemy. You can fire a few extra bullets to put them out of their misery or curb-stomp them. There are many executions to perform and you also have the option of picking them up to use them as a meat-shield. Getting close enough to utilise this feature is a rare occurrence, since most gun-fights occur at range, meaning you have to run into enemy territory.
There's some new weapons such as the flame-thrower and heavy weapons such as the chain-gun or mortar which slow you down and prevent you from roadie running. These new weapons mean there are a few new Locust soldiers which carry these weapons. Additionally, there are Blood Hounds (mounted units) and Tickers, which are small creatures that scurry around, acting as suicide bombers. There are no Berserker or Kryll, the latter's breeding grounds apparently being destroyed by the bomb in the previous game. The Hammer of Dawn weapon doesn't make an appearance until the end. Grenades can now be planted on surfaces and used as proximity mines.
There are many sections that break from the main cover-based shooting game-play such as driving a vehicle such as a tank, manning a turret to defend an area, or even just walking around without much going on. I tend to find sections like that a bit boring and mindless at times, but at least the game attempts to add variety.
You will spend the most time with Dom, but will have moments with a larger squad. There's many returning faces plus a new rookie soldier who is a relative to Carmine. In the original game, you had the option of telling your squad members to attack, hold off, or regroup. I found these actions useless since they either refused to co-operate, or did a okay job without these orders. These actions have now been scrapped. The AI seems to have been improved, and they will even lead the way rather than waiting for you to work out where you need to go. It's a much more user-friendly experience and there's rarely a frustrating moment.
There is an extra difficulty level but it's a bit misleading. The original game's easiest difficulty, Casual, was really hard. A 'Normal' difficulty has been added which only has a few difficult areas. If you want to replicate the difficulty of the original game, then you need to be picking one of the harder difficulties.
Gears of War 2 is a great example of how a sequel should be implemented. Removing many of the problems that the original game had, then giving it a nice visual polish leads to a very enjoyable game. It still lacks story and ends on an anti-climax but makes large improvements in many other areas.