Years ago, when I was but a wee lad, the only console gaming system I had access to was an ancient Atari 2600.
My sister and I would have hours of pixellated, low-graphics fun, regardless of the fact that all the other kids had NES systems (or even the then-brand-new SNES) and the fact that one of the joysticks was a piece of junk that barely worked. One of our mutual favorite games, mainly because it was just about the only one we could play together, was called Combat.
Combat was a game that featured three "styles" of play; tank, biplane, and jet battles. The format was a one-on-one "duel" in which a timed battle took place. Each player had to "kill" the other as many times as possible. Generally, whoever hit first could hit the other player a few times in succession, and very one-sided games were possible. (This was more of an issue in the tank battles.)
The tank games were probably the best, because they featured what was colloquially labeled "tank pong": The shells the tanks fire bounce off of objects in the environment. (The normal mode featured ultra-short-ranged shells; this was super-boring, because it took forever to close to range and then whoever squeezed off the first shot usually won. The bouncing shells had extremely long ranges, especially by comparison; in fact, they didn't do damage until they'd bounced at least once, in order to make sure that the players didn't KO each other right out of the gate.) This was probably the best part of the game.
Why am I talking about this?
Because, except for the lack of two-player, Tank Destroyer is the game I've played which probably comes closest to what an updated Combat really should be.
Granted, there's no bouncing shells, but now, the game lets that short-ranged combat be interesting. (Although a variation or clone with super-long-ranged bouncing shells that could fly from one end of the map to the other fifteen times over would be awesome.)
The reason for lack of two-player is obvious-the smooth mouse-and-arrows interface just wouldn't work in two-player games. But the sacrifice of this potential feature (not that a free browser game would be likely to have a two-player mode) is made up for by its interface, and by the interesting tank combat.
In Combat, your tank shot forward. Given the limitations of the Atari 2600, this was understandable, logical, and necessary. In Tank Destroyer, you get a limited notion of just what tank combat is really like.
Tanks can drive forwards or backwards with ease, and "front" can mean either your poorly armored rear or your well armored front. (I'm assuming that there must be some degree of variation in armor values, because I tend to have more success when attacking the rears of other tanks while presenting other tanks with my front.) Changing directions is quick and simple-just "switch gears" and you'll be going the opposite direction.
Turning is slow and awkward, just as with real tanks (or any big vehicles). Of course, the trick is, you don't have to shoot the way you're going. The mouse makes this easy and intuitive.
You have a few extra weapons at your disposal besides your main gun. At the start of the game, you have two rockets and five mines. Rockets (put the cursor directly over your target and hit F-don't be surprised if you still miss, though) are clumsy weapons with a decent punch, while mines (dropped by the Space bar) are strategic tools which can instantly kill the tanks from the first wave without you ever seeing them, and which can soften up the tougher foes considerably.
Better still are the powerups enemies drop and the upgrades you can buy. (All enemies drop exactly one powerup; stronger enemies give you more money.) Some of the powerups are just run-of-the-mill healing and ammunition items, but there's also an energy shield which protects your tank. You can also buy upgrades on the amount of armor you have (although the description of the item is misleading), the speed of your tank, and also completely new weapons. (And if you like your old one better, don't worry, you can apparently switch them around.)
The shop is also the pause screen, by the way.
When you've purchased the full armor upgrades, your tank looks like this; tellingly, the wave four enemies also look like this. (The intermediate colors are desert tan and turquoise.)
As I've continued playing this game, I've discovered two things. First, the speed upgrades are well worth the money; at only $350 a pop, they boost your speed from "as fast as anything" to "holy moly that's a fast tank." Since the first four waves, at least, of enemies get tougher but slower, this becomes increasingly advantageous. Second, if you have the sound on, the tank's shells make a "ping" noise on enemy armor. If you use the map to guess where enemy tanks are, you can hit them from halfway across the screen-important when the enemy is able to tear you to pieces at close quarters. (Which they can.)
I'm not terribly good at games like this, but I love playing them anyway.