History YMMV / DefenseGridTheAwakening

** 'Firebug', which requires you to beat an Advanced mission using ''only'' Inferno towers. What makes it so much harder than 'Gun Crazy' and 'Shell Shocked' (the equivalent achievements for Gun and Cannon towers) is that while Gun and Cannon towers are [[JackOfAllTrades basically good against everything]] and it's quite plausible to beat a level with them alone, [[TierInducedScrappy Inferno towers simply suck against anything other than Swarmers]] (or particularly large groups of Walkers) due to their incredibly short range and pathetically low single-target damage. It wouldn't be so bad if you could get the achievement for a Grinder mission where you have to fight nothing but 99 waves of Walkers (although even that is frustratingly difficult) but they don't count.

* ThatOneAchievement: 'Firebug', which requires you to beat an Advanced mission using ''only'' Inferno towers. What makes it so much harder than 'Gun Crazy' and 'Shell Shocked' (the equivalent achievements for Gun and Cannon towers) is that while Gun and Cannon towers are [[JackOfAllTrades basically good against everything]] and it's quite plausible to beat a level with them alone, [[TierInducedScrappy Inferno towers simply suck against anything other than Swarmers]] (or particularly large groups of Walkers) due to their incredibly short range and pathetically low single-target damage. It wouldn't be so bad if you could get the achievement for a Grinder mission where you have to fight nothing but 99 waves of Walkers (although even that is frustratingly difficult) but they don't count.
** To make matters worse, the general consensus is that there's literally only ''one'' mission in the entire game where getting the achievement is even ''physically possible-'' Barrier to Entry. ''Any'' map featuring [[ScrappyMechanic fliers]] is automatically a no-go (as, unlike Gun and Cannon towers, Inferno towers can't hit fliers at all) a lot of the maps without fliers still have wave and grid layouts that simply make it impossible for you get enough firepower in position to win on Challenge with only the piss-weak Infernos to draw on, and the earliest and easiest missions like Assessing the Threat simply [[TheBattleDidntCount don't count for the achievement]] [[BecauseISaidSo because they say so]]. And even Barrier to Entry is ''ridiculously'' hard to beat with only Infernos, largely because of an early wave of Bulwarks whose shields let them ''laugh'' at your firepower. Notably, the same achievement appears again in the sequel, but is ''much'' easier because of the inclusion of both tower upgrades that can improve the Inferno's damage, tower bases which can include Disrupters that strip enemy shields, and the complete removal of fliers.
** From ''[=DG2,=]'' 'Master Strategist', which requires you to earn 100 Gold medals. Problem is, the game just isn't that long- you'll have unlocked the ''second'' most grindy achievement ('Xenocide', which requires you to kill 50,000 enemies) ''long'' before you've played enough levels to earn 100 Gold medals. 100 levels is a ''lot'' of play, especially when that by necessity includes challenge modes. Making matters worse, all the medals have to be acquired ''on the same difficulty level-'' something the game [[GuideDangIt didn't consider to be significant enough to tell you about]] before you tried making up the medal numbers by replaying stages on Easy.

** From ''[=DG2,=]'' 'Master Strategist', which requires you to earn 100 Gold medals. Problem is, the game just isn't that long- you'll have unlocked the ''second'' most grindy achievement ('Xenocide', which requires you to kill 50,000 enemies) ''long'' before you've played enough levels to earn 100 Gold medals. 100 levels is a ''lot'' of play, especially when that by necessity includes challenge modes...

** Decoys. Reasonably though and they give aliens cloaking ability and without a Command tower (or Disruptor in the Boost tower in ''Defense Grid 2'') the other towers will focus only on the Decoy ignoring the others until it dies, by that point aliens can be either past through you main line of defenses or running away with a core. To top everything enemies cloaked by the Decoy are practically invisible to Meteor and Cannon towers.

** To make matters worse, the general consensus is that there's literally only ''one'' mission in the entire game where getting the achievement is even ''physically possible-'' Barrier to Entry. ''Any'' map featuring [[ScrappyMechanic fliers]] is automatically a no-go (as, unlike Gun and Cannon towers, Inferno towers can't hit fliers at all) a lot of the maps without fliers still have wave and grid layouts that simply make it impossible for you get enough firepower in position to win on Challenge with only the piss-weak Infernos to draw on, and the earliest and easiest missions like Assessing the Threat simply [[TheBattleDidntCount don't count for the achievement]] [[BecauseISaidSo because they say so]]. And even Barrier to Entry is ''ridiculously'' hard to beat with only Infernos, largely because of an early wave of Bulwarks whose shields let them ''laugh'' at your firepower.

** The Landing Pods in ''Defense Grid 2''. These things always drop ''right next to the core housing'' and lay aliens there. It cannot be destroyed but all damage dealt to the Landing Pod mitigates to the aliens it spawns, but long range towers (Cannon and Missiles) have the tendency to ignore them and keep firing on other aliens and sometimes you don't have the option to build short range towers close to them, to make things worse some of the Landing Pods barely stays there for a couple of seconds before starting spawning aliens. Landing Pods become even more dangerous in Frozen Core challenges as if an alien so as much touches the core, it '''won't''' float back to its housing.

* ScrappyMechanic: Fliers from ''[=DG1.=]'' They don't follow the path that all the other units do, are immune to the attacks of all towers except Gun, Cannon and Missile (which are [[CripplingOverspecialisation useless for anything EXCEPT killing fliers, which they do with ABSURD efficiency]]), and if they grab a core then it's lost forever even if you shoot them down. They're so radically removed from the rest of the game's mechanics (and such an utterly token addition, basically just requiring you to waste a few hundred resource on a couple of level 1 Missile towers to be able to ignore them completely) that they're almost an OutOfGenreExperience and were ''completely'' removed from the sequel, with absolutely ''nobody'' missing them (Missile towers were repurposed as a more precise variant on Meteor towers).

* ContestedSequel: From removing the interest resource gaining mechanic to the implementation of micro-transactions in community maps, let's just say some fans of the original didn't take kindly to the sequel.[[note]]Classic Open mode was added in 03/24 which features ''[=DG2=]'' maps using the same interest mechanic of ''[=DG1: The Awakening=]''[[/note]] On the other hand, some of the changes and new features (like tower bases, variable beams to choose from and the removal of fliers) were appreciated. The first game is definitely better-regarded, but the second is still considered a decent tower defence game.

* ContestedSequel: From removing the interest resource gaining mechanic to the implementation of micro-transactions in community maps, let's just say some people didn't take kindly to the sequel.[[note]]Classic Open mode was added in 03/24 which features ''[=DG2=]'' maps using the same interest mechanic of ''[=DG1: The Awakening=]''[[/note]]
** It didn't help that the game received almost no support compared to its predecessor, getting little to no post-launch content or bug fixes, meaning that the original is actually the bigger game.

* ThatOneBoss: Crashers are this for the unaware. What makes them so difficult is the fact they very rarely come alone and by the time they die they can be midway to the exit carrying three cores and leaving them as easy pickings for smaller, more fragile enemies. The worst part about Crashers? Later on they come in '''packs'''.
** Turtles are ''stupidly'' tough for their speed (not as tough as [[StoneWall Crashers]] but ''far'' faster) and the aliens they carry inside them often cause as much trouble as they do. On later levels they can bring '''Crashers''' and '''Rumblers'''.
** Rumblers. Racers on steroids that are as tough as high grade ''Rhinos'', without Temporal towers it's not uncommon for these things to just blaze through everything, pick cores and leave before the player even has a chance to built another tower.
** Seekers later on becomes this. They can start summoning things like Racers and even high grade ''Bulwarks''.
** Juggernauts are just like Crashers, but with '''[[UpToEleven shields]]''', although they are very slow they take forever to bring down even with Level 3 Towers.
** It's quite telling how prepared you need to be when pretty much every boss enemy is listed here.