You're overplaying the versatility of the game quite severely. Like you just said, there's only three methods of attack; spells, troops and the ballista. None of them will really get you the win, at least not the 5 star win, on their own and you have to combine the three constantly.
There's no way you can just ignore the ballista, at least not before your troops and certain bonus rooms are level 8-10 (which none of mine are so I don't know).
The thing about the game is that it never locks you out from something useful, while using another tool, basically. Every option has a layer of depth to it that can make up for a lack of use of one of the other weapons. Bonus room usefulness can be mitigated by skilled gameplay; they simply serve to ease burdens, no relieve you of them.
So, while most games like this would have you rely on each option 33% of the time, you can shift your dependencies as you need here, and still get the win (yes, even the 5 star, depending on stage and bonus objective.)
Examples:
- Hero has combos, which provide knockback on final hits. They also can "advancing strike" combo (by holding forward while striking) or root in place (hold no direction), thus allowing you to either hold a line, or push it. They have melee that allows headshots, can block ballista blows, and their B special can be STUPIDLY powerful when charged up, especially depending on the hero. They can also jump and guard cancel melee (better than some Beat-em-Ups, oddly.)
-Ballista has it's heavy fire special mode, achieved by getting 5 kills in quick succession. At first, this is HARD, because all you can do is basically headshot, and hope for the best. Eventually, when you get better specials, you can achieve the 5 kills in one shot, and then ARROW SALVO / ROCK SHOWER / Etc the heck out of the battlefield, or the enemy castle. This offers an absurd amount of fire power, and none of this seems to count against your accuracy, because if any part of a cluster weapon hits (a soldier, a castle), it counts as no miss. Thus, you can use the Ballista as a last ditch, and win a stage with no misses, if you find distanced aiming too hard without a targeting line.
- Bonus: Since you can precision aim with the D pad, you can actually set the Ballista at 1 point in the battlefield (that allows constant headshots) and keep it there during the entire battle. Feel out the first few shots in far zoom, landing body and head shots, and once you find the headshots, Keep it there! Combining these methods does let you step over almost all the annoyances of trying to get high accuracy in large stages.
- Spawned soldiers come in large variety, and all move at different speeds. Also, different ranged soldiers can either attack the fort door (for easy flag victories), or just keep soldiers at bay. You can either play the "constant soldier" outpout style, a ranged control style, or rely on a few brutes, that you power through to the door. You can level different sets of soldiers (on Knights, I depended on champs and healers, on Vikings, druids, as their range-magic + constant advancing is unlike any other class), and have success in your own way.
And this is all supplemented by the ability to build your own skill layout, AND castle (Or just pick from well-made detail castles). So while I like headshot harpoons, you might rely on 3 shot harpoons, or only auto-target / close range shots, and a whole different set of soldiers. While I want 2 heros to alternate between summoning, you might render this option moot for me, by relying on dragon / gryphons + high level magic.
And, come on, you know what I meant about the vikings campaign. They reset all your shit back to level 1, essentially. That's like saying "welp, your party died lol" halfway through an RPG and making you start over on leveling and getting gear back. That's not fun, it just makes the first half feel worthless and pointless.
This would be true... if the campaigns earnings and levels didn't carry to Multiplayer and bonus modes. As it stands, I felt the 2nd campaign felt like a free DLC campaign. You never LOSE anything, you just get a new set of toys to play with. Basically, all they're doing is making sure one doesn't assume the Vikings are just palette-swaps of the knights, by making you watch the (highly accelerated) progress of a 2nd skill tree.
I think it felt very similar to my (limited) time playing different races in StarCraft; each group is the same on the outside, but different in detail. Thus, each SP campaign goes through the whole "lvl 1 to max" progression over again, but they limit the pain by making sure each classes starting options offer a bit of what the last classes max options made you wait for.
I would have been satisfied with the 1 campaign, for a $10 game, so I just screamed "BONUS!" and proceeded along my merry way, surprised at the amount of value this game offers...
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Seriously, I don't make these claims for Castlestorm lightly; Playing through a solid amount of offline Co-Op and VS, on varied difficulties, and playing campaign stages on both difficulties, I'm very impressed with how deep each option is.
In previews, I anticipated a fancy Angry Birds X Boomblocks, with timed troop management and auto-playing hero summons, with click-and-forget magic spells. But the actual game is SO much deeper than that.
I'll accept that the game might be "grindier" than I felt though.
I liked playing the multiplayer, retrying stages, and playing each stage on varied difficulties, all while chasing max stars, and playing the variety of bonus Survival modes. So a person who wants to power through the game might have a more difficult time, especially if they play on Hard exclusively. But considering that ANYTHING you do in ANY mode all leads back to money for the campaign / Multiplay, the reliance of grinding is severely reduced.
All this met by a very solid technical underbelly (miniscule loading time, lightning quick retry / restart options, gourgeous overall graphics full of quality textures and effects, no frame drops, high enemy /projectile counts, and lots of physics based destruction and projectiles), and robust multiplayer and single player options, makes it a stand-out in the XBLA library to me.