Tactics 100 Live
(Note that I'm only going to talk about the single-player part of this game, since that's all that I've played. This is true in general, in fact -- I tend to avoid games which require playing with other people. Also, this is the last of the games that I had played before joining Kongregate, for what that's worth.)
Tactics 100 is brought to you by the same designer as Drone Wars, which makes this an object lesson in what genres are well-suited for Flash games, because this game (while not spectacular) is a fun little diversion, and a vastly more enjoyable game than Drone Wars.
The basic principle is pretty simple: it's a turn-based strategy game, where you have units of various types (knights, which are slow melee units capable of dealing and taking a lot of damage; rangers, which are fast ranged units but do little damage; mages, which are slow and vulnerable but can use their magic to deal large amounts of damage to multiple targets; and clerics, who heal other units) which battle it out on a square-grid battlefield. There's a fair degree of tactics involved; for instance, attacking units from their flanks or rear is generally advantageous. There's also high and low ground, though the battlefields are organized in such a way that this almost never comes into play.
One nice thing is that your army is fully customizable; if you choose to create your army from scratch, you're given 100 points, which you can spend either on buying units or on upgrades for the units you've already bought. (You can also choose to start working from the default army, if you prefer.) So you can build an army with lots of relatively weak units, or an army with a few super-powerful units, depending on your preferences. Quite a lot of the fun in this game is derived from tweaking your units to try to get the best combination psosible. (This process is somewhat aided by the fact that some upgrades are obviously much more useful than others, as you will rapidly discover.)
The single-player mode features ten successive fights against different enemy armies, some of which will provide a tough matchup and some of which are pretty much pushovers. Fortunately for those of you trying to earn the hard badge (which requires beating all ten without losing a single unit), the AI is not very smart, so once you've worked out a good army, rolling through all ten is not terribly difficult. The graphics are nice, the sound effects are pretty good, and the music isn't bad either. The game does tend to run a little slow on older computers, but that's not a really big problem for a strategy game like this.
Overall, this is a nice little game, but the replayability of the single-player mode is hampered by the fact that it's a little too easy. Perhaps the multiplayer feature would help make up for this, but that requires playing with other people.