Very interesting, solid, deep TDG. Needs an end.
I liked this game a lot. It's still not my favorite turret defense game, but it's among my top 5. What I liked most was probably the combination of small tile size, generous unit ranges, and large, diverse maps. I had to restart a few times because the game DOESN'T LET YOU READ THE UNIT DESCRIPTIONS before you build your defenses for the first time, but the units themselves are very simple and straightforward.
Once you notice the similarities to Xeno Tactic, you'll figure out that five seconds is plenty of time to throw down some walls and a couple of machine guns and start building the winding intestinal path-of-most-resistance from the last ground unit's spawn point to your base.
The difficulty curve here is impeccable. Early stages are hard if you just build a few isolated turrets, but become very easy once you get a strategic maze up and running. Each unit has its own tactical advantages, and upgrading is costly, but efficient enough to be worthwhile. (Twice the damage for less than twice the price!) Enemy units get stronger with each wave, including some very powerful bosses, but the increase is so gradual and steady that you never actually experience a "that's not fair!" moment until somewhere around level 120 (my, time flies!) when the gradually-growing armored column finally starts making progress through your maze faster than your defenses can dish out punishment.
And that's the ultimate flaw in this game. You're fighting the tide. You can't win, ever, no matter how long you play. Worse, it's raw statistics, not skill, that dictates how far along any player can get before eventually being overtaken. Pretty much anyone can get to wave 100, and literally no one can make it much further than that. The tools you have to work with simply do not provide for that possibility.
At least Xeno Tactic (and, for that matter, Desktop Tower Defense) gave you a goal, even if that goal was completely unreachable except through the most fiddly borderline-cheating maze-manipulation and the one specific build order that would net you enough profit to afford enough air defenses to wipe out that final wave of super-fighters. In this game, there's no bullshit final wave weeding out all but the most anal-retentive defenders, but there's also no goal, period. I would have liked to see an endgame. "See how far you can get" is best reserved as a personal, optional goal for players who have achieved everything else the game has to offer. It should not be the game's only goal.
That aside, this game had a lot to offer. I loved the quick gameplay, long unit ranges, and incredibly diverse number of possible build combinations. I would have liked to see some more upgrade options, but more than anything this game needs some Achievements. Victory at level 100 on the first map unlocks the second map. Maybe tack on a story mode.
To the author: even if it's just a little "Congratulations, you won!" pop-up when you hit level 100, that still goes a long way towards making the game as a whole feel more satisfying.
See also: Bloons Tower Defense 3 for a case study in adding level-specific win states to an otherwise simple TDG, or Gemcraft for a great example of how meta-gaming goals such as Achievements and Player-Managed Risk can make score-maximization much more rewarding than just mere survival.
Thanks for a well-designed Turret Defense game. If only I had a reason to keep playing it!