Very well-constructed game, fits nicely with the first in the series (and excellent cross-over) with decent script and top-rate voice acting. Gameplay is well-balanced and provides a challenging mix of shooting and driving, with considerable tactical depth particularly in arming and levelling up. The music is good and changes neatly in context (e.g. when stopping to perform at task) although the main theme gets a bit repetitive at times - as do some of the voice phrases, for instance "You deserved that!" sounds a bit funny when repeated several times in a row!
Now follows a complaints announcement: I had the "key gets locked bug". Don't know what triggers it, although sometimes it's accompanied by a browser (Opera in Win7) message about NG running in Full Screen. When I notice the car is stuck turning or braking, I can free the controls by a mix of firing a shot, pausing and resuming. It's annoying, sometimes lethal (if car is in bad shape and hits something while out of control) but acting fast to resolve it means gameplay is manageable.
In the voice acting, it's nice that there are several different phrases for each type of situation encountered, and the game responds intelligently to which character is driving/shooting, but it would have been easy to implement a rule for "don't repeat the same phrase twice in a row" to reduce irritating repetitions.
Sometimes in-game sound effects get looped. This happens most often after getting zombie-grappled. For half an hour or more I can stuck with "Get it off me! Get it off me! Get it..." or incessant quasi-erotic groaning, that continues regardless of other character speech or sound effects. No amount of pausing or music/sound toggling seems to kill it - once the game is resumed and the sounds are back on, the loop comes back. This happens quite rarely but is super-annoying when it strikes.
In terms of gameplay some reviewers complain about the "grind" to build points and experience. At first I felt the game involved a lot of this, but my tactics involved a lot of stopping and shooting (to build up character experience), picking zombies off one-by-one. Only later did I realise that combos give massively more points, and hence allow you to upgrade car and guns earlier. Tactically, combos are easiest reached from a more fluid and exhilarating playing style - building up speed, shooting on the move, and using the bumper as main weapon! Characters' weapons experience builds up slower this way, but upgrading - and crucially, the game as a whole - moves faster.
My complaint is that the game doesn't make it easy for players to discover this playing style, as the most straightforward way to kill zombies and gain experience at the start is the "park and shoot" method a lot of reviewers recommend, which soon bogs down to moving just 100 meters at a time, and frequently getting overwhelmed by zombies. A playing section earlier in the game that encourages players to pick up the art of combo-making, or just a note in the Survival Guide about the disproportionate value of combos in point-scoring, would help players get the most out of this hugely enjoyable game.
Character skill levels are important, but the only ones easily found are Driving and Toughness, shown at the driver-selection screen. Various weapon skills also build up with experience (handling, reloading etc) but I only see these when they are updated, and it's hard to remember who is good at what with which gun! The "who drives" choice is also a "who shoots" choice, so it'd be logical to display information about their shooting skills, as well as which guns are equipped, and how upgraded they are. I accept this would cram the driver-selection screen if they were all displayed by default, but if you could click a "show weapons" button or something that would help. It'd be cool if that info was available in-game too, especially when upgrading at an arms crate or police station. Whether you want to tune up a gun the character is weak at, to make up for their ineptitude, or whether it's to make a character a specialist in one super-weapon (bought upgrades plus experience working together), that decision is interesting and it's a pain to have to work from memory.
There are lots of similar tactical choices in the game - is it better to develop a specialist gunner and specialist driver, or have two all-rounders with a focus on rapid-switching, complementary firepower style and combining their limited ammo? Best to make full use of all available repair/upgrade/reloading stops, or better to scoot it and stop infrequently, hence reducing exposure to zombies and airstrikes? Best to have a couple of excellent guns and avoid using the weak ones, or a more even spread that makes better use of the full range of ammo types but lacks that lethal edge?
Unfortunately the game loses a lot of the replayability of the Story Mode, due to lack of opportunities to explore alternative avenues for those choices. Once you are upgraded beyond a certain point, restarting Story Mode from the beginning feels pointless - you are overpowered, and the challenge of progression is removed. Several times I wanted to compare the effectiveness of different strategies and restore the challenge of surviving the earlier levels, so I cleared my flash cache before restarting. In an ideal world there would be different save slots, so a "side by side" comparison is possible. But a "Start from Scratch" option, with a big "Are you really sure you want to wipe out all your upgrades and experience?" warning, would add to replayability without manual cache clearance!
I found the game runs smoothly without lag, as does the intro cut-scene, but the mid-game and end-game cut-scenes don't work properly most of the time. They usually lag, freeze, stutter frame by frame, and the sounds don't work - not in sync with the visual, sometimes incomprehensibly sped up or garbled. Occasionally the cut-scenes simply crash altogether. In Story Mode, this usually jumps to the next level (e.g. ramp-driving and helicopter-boarding cut-scenes) but a crash in the final cut-scene just goes back to the main menu. However, in what is BY FAR THE MOST IRRITATING BUG I HAVE EVER SEEN IN A FLASH GAME, any crash in the cut-scenes in Hardcore Mode goes right back to the start!!! When you have spent several hours battling through without losing a life and get through to the helicopter-boarding cut-scene, seeing Level 1 rather than the final timed survival battle, is absolutely infuriating. I can confirm this happens whether I let the cut-scene play out, or if (when I see it starting to fail) I press "Skip". I can only forgive you because the game you have made is so awesome, but that's where your half a star went.
I have lost so much sleep playing this game instead of going to bed. It's surprisingly easy to lose track of time playing it, because it is so non-stop! The first game in the series had breaks between levels, when you got the upgrade screen. Now, the in-play upgrading and smooth progress between levels has removed such natural pauses in play altogether. That's more fitting for the storyline, but not good for casual play or indeed getting much sleep. IRONICALLY A GAME ABOUT AVOIDING GETTING TURNED INTO A ZOMBIE, HAS TURNED ME INTO A ZOMBIE. That's an impressive testament to your game-making skills. Many thanks, despite my gripes.