Pros & Cons:
Pertaining to My short list below.

While the lighting is dynamic, shadows are sharp and textures are above the average, the engine (which powered Halo 3; even it looked a tad aged upon release) is showing its age, with no anti-aliasing (say goodbye fine-lined objects) and primitive, simplistic geometry. The latter issue is most evident in character models, especially their close- ups, with awkward facial animations and lip-syncing, low-res texture maps that try to pass for secondary details (like hair) and relatively blocky protrusions where rounded heads and facial features should be. However, despite some light hitches and pauses here and there, the framerate stays solid and load-times are brief; and areas like the invaded African zoo with savanna plains, along with the atmospheric, ruined nighttime streets of New Mombasa show a different, more relatable side to Halo's universe. As always, the exaggerated physics make explosions (which still look nice) fun to watch, as enemies fly dozens of feet, and little things like reflections bouncing off the water or Ghost hulls don't fail to impress—overall, it's the best looking Halo installment yet; but it will be interesting to see what they do for Halo Reach.

While its visuals lack technically, it makes up for it in scale (roll-over first for second).

The game starts about as non-traditionally as a "Halo" game could, with an immersive HEV (Human Entry Vehicles) drop from the sky, and then, at first, no enemies in sight and a focus on...exploration *gasp*! After you upload a map of Mombasa city from its AI interface, Vergil, to your NAV screen, it soon balances itself out, as you proceed to use your new VISR in conjunction with the map to navigate the city while you combat patrolling Covenant. As an ODST, you're not even close to as capable as Master Chief, with an inability to jump as high or from long distances without getting damaged, you can't duel wield weapons or throw out secondary items (like Bubble Shields) and your healing abilities are markedly diminished, with a bar similar to that of the first Halo's health system; after a certain (quite low) damage threshold, your stamina will wear down, causing each hit after to sap the bar itself. If you take cover, your stamina will replenish, but the bar won't, meaning if you don't find a health station/pack to restore it, you'll take less and less hits after stamina depletes.

This vulnerability is heightened by the haunting, isolated atmosphere of Mombasa city streets, and even furthered by the moody, melancholy orchestral score reminiscent of what you'd find (never thought I'd say this) in the Kingdom Hearts series; the tone set by these portions is superbly executed, and adds a fresh feel to the franchise. Despite your less resilient nature, you aren't totally helpless, with new tools that help counter your weaker physicality, including the aforementioned VISR night vision mode, which outlines objects in yellow, enemies in red and allies in green, along with the overhead map on your NAV screen that shows alternate routes, accessible sector doors and the beacon to your next objective—this can also be summoned to your on-screen radar by pressing up on the d-pad at any time. To go along with the more tactical feel, default equipment is a (weak but accurate) silenced SMG, and the (triumphant!) return of the powerhouse pistol from the first game, complete with zooming function—this is great for downing the smaller enemies with swift headshots.

Nighttime combat with new VISR, and moody exploration (roll-over first for second).

All of this, along with the fact that you need to conserve your ammo (if optional Audio Logs are collected from certain telephone booths, secret weapon caches will begin to be marked on your map, with Human weapons and even a four-wheeler Mongoose for faster travel—in one area, you can also procure a Ghost hovercraft—to even out your lack of ammo and maneuverability) and that you can use your map to flank or simply avoid the patrolling enemy altogether (while the objectives are linear, city navigation isn't), it encourages a slower, more strategic approach to gameplay. After reaching a beacon, you'll inspect the article in question—a ruined helmet, sniper rifle, etc—which will then prompt a flashback putting you in the shoes of that ODST team member and showing how that object's condition came about. These flashback sequences contrast nighttime portions by focusing on flat-out action, and have far more in common with those in Halo 3. And most of that installments weapons are at your disposal, including returning vehicles like the Ghost, Warthog, Brute Chopper, Scorpion and Banshee—all of which (devoid Wraiths) can be hijacked at any time.

These more action-packed sequences are on-par with the best action set-pieces in the series, as you participate in huge scale battles while devastating enemies with a tank, destroying an entire bridge with Covenant enemies packed on it, and you'll even take down a giant Scarab with a lone Banshee. However, in keeping with a markedly more vulnerable state, you will find yourself trying to hold the area more often (usually with emplaced turrets that you can still pull off and lug around), and as always, you really can't have a favorite weapon, if you wish to survive, that is. As for AI, allies are good at staying out of your way, taking down a few enemies and drawing fire; just don't let them drive. And enemies are as relentless as ever, constantly repositioning, flanking, firing very accurately and rolling from grenades and vehicles; they'll even warn each other depending on what type of weapon you're carrying ("Sniper!", etc). Negatively, the campaign is short, at a maximum of five hours, and since you're faster at lugging around turrets than Master Chief (which gels with the ODSTs' lighter nature), it's very puzzling as to why they still haven't added a sprint.

The narrative does a good job of juggling each of the six ODST squad members, all of whom are very different, giving some entertaining chemistry, especially between the team's offish captain, Victoria, and her former smart-aleck flame, Sergeant Buck. The teams' interaction is enhanced by the high-profile voice acting, with those like Nathan Fillion, Adam Baldwin, Alan Tudyk (all three actors from cult sci-fi hit, Firefly), Nolan North (of Uncharted fame), and Trisha Helfer (of Battlestar Galactica) providing their voices and solid performances for each of the five (not counting the voiceless Rookie) ODST. Both Dutch (a religious, gun-loving cowboy) and Mickey (a ditsy demolitionist) add some comic relief; each flashback story, with adjoining characters, is unique and interesting; and after you (the Rookie; a clever method of immersing you in the role) finally do catch up to your team, what remains is a heart-pumping race to escape the Covenant invaded city, in what ends up being a mission vital (let us just say the city's AI, Vergil, is integral) to the core plot line of Halo 3.

Daytime flashback sequences retain a more traditional Halo play style; all-out action.

The difficulty on default Normal is a bit above moderate, with more Jackal snipers and giant Hunters, along with higher enemy number and cloaked Brutes as you get further into the nighttime city sequences. Flashback portions are jam-packed with enemies of all types, as well as the vehicles that bombard you from every direction, all the while dropships keep sending in piling waves—and as always, you constantly have to switch between fresh vehicles and weapons to survive. Add all this with your low resilience, scant health packs and, for both night and daytime sequences, most often far and few between checkpoints, the campaign will take some decent skill to complete. However, the difficulty is balanced out by an Easy setting, which is suitable for the more casual players, especially if played in co-op with a friend, and on the opposite spectrum, the more veteran Halo players will probably want to bump it up to the Heroic difficulty for a challenge closer to an upper-moderate "hard" mode.

After you complete the relatively short 5 hour single-player campaign, you can (if you haven't already) go back and collect all 30 of "Sadie's Story" Audio Logs, play through again in single-player, split-screen (two players) or online co-op (up to four; free-for- all competitive scoring is an option) on a higher difficulty with Skulls (no respawn, no HUD, enemy with twice health, etc.) enabled for even more challenge, or survive the new Firefight mode. Firefight plays much like Gears of War 2 Horde mode (a trend as of late), with 10 maps (some are unlocked, along with character skins for this mode, as you play through single-player) and the objective to survive random enemy waves as long as possible while racking up points and adapting to equipped Skulls, which are also randomly set for each round. Sadly, neither co-op nor Firefight mode (which you can play alone; no thanks) have matchmaking; this means if friends aren't accessible that minute with the same game in their systems, you're out of luck, which is truly a missed opportunity (on the plus side, its second disc does contain the entirety of the Halo 3 multi-player, including all of the DLC up to this point).

Closing comment:
So overall, this truly does breathe much needed life into the Halo franchise, including a new take on the formula, like brilliantly executed city exploration, a more strategic approach to gunfights (in necessity of your more vulnerable nature), causing you to fend off enemy Covenant in more creative ways—breaking up the shoot, shoot, shoot staple of the series—and still plenty of typical Halo action to keep things comfortably familiar. The story also shows that characters in this universe can be quite endearing with or without the likes of Master Chief, and this goes for Sadie's Story, which gives an intriguing look, among other things, into the workings of Vergil (an actual friendly AI construct) and his friendship with the title character. And while the campaign may be short-lived, along with the fact that there is no multi-player matchmaking, with its fresh approach and changes for—surprisingly—the better, this is a worthy addition to the Halo franchise, and in turn, worth any Halo fan's time.