- GPT offers will almost certainly center on clearing Campaign stages. If they're about camp level in any way, don't do them, building takes forever. Clearing Campaign 50 F2P in 30 days is very doable, though. Campaign 60 is possible but you'll need to play at least a few hours a day every day unless you want to spend probably at least $10-20 USD to speed things along. I don't think anything beyond that is worth spending money to go after, unless you somehow get a term of 60 or 90 days.
- The 99 cent "first top up bonus" is worth buying right at the start. It provides the convenience of not having to watch ads for EXP Bot, but the real benefits are it opening up the 4th robot slot (HUGE help and can't be done any other way) and providing a piece of equipment that boosts EXP gains by 10% on the 3rd day after buying it. There are some other helpful purchases but I'd weigh them as you progress depending on your circumstances rather than getting them right away
- Join a guild ASAP. There are a lot that are tailored to and welcoming to new players. Even a lowbie guild gives you a ton of boosts
- Two things help you to survive combat stages in this game: your "build" of optimizing equipment and upgrades to achieve a certain survival strategy, and positioning in the level (knowing when to either use terrain to obstruct incoming zombies or stay out in the open to be able to get to the outside of a mob and circle them). This channel shows you some of the good places to stand to take advantage of terrain (this one has a few specific later stages too), but this strategy mostly centers on using something like EXP Bot to gather gems and does become outmoded in some levels (will get into that more below). It's pretty reliable to survive and grow early in the game though.
- A "build" that you're sort of naturally steered toward from the beginning is focusing on freeze powers, which actually stays very potent all the way through the game. What does "build" mean? Mostly what you pick and level for weapon, equipment and robot pals, and then the upgrade path you choose while in each level. First, use and grow the assault rifle as it provides a natural boost. Also craft up freeze equipment, which not only boosts ice attack but also allows you to run through frozen enemies unharmed. The one exception here is your weapon; use freeze grenades at first but switch to the S-rank Carnage Grenades as soon as possible, as they're way more useful. Get one attack and one defense robot with freeze powers (such as the Ullr Drone and Frost Penguin); we'll save the other two slots for Dark powers, discussed more in a bit.
- Early game while you're focusing on freeze, the best strategy for campaign levels is usually to find a place to stand that's shielded (keep in mind enemies can't spawn behind you when you're near enough to an edge or corner of the map) and just hold everyone off from there while EXP Bot or a similar support bot collects the droppings for you periodically. Take the first freeze upgrade, which adds it to your bullets, and maybe the "fire 3 bolts when your clip is depleted" or "enemies lose 5% health when frozen" if nothing better is available, but the other ones aren't really necessary. Focus on reload (but not the Miniclip ultimate), number of projectiles, ammo count and the "slayer" bonus boosts for bosses. This strategy gets outmoded once you get into the 30s and 40s however, as enemies are introduced that counteract this (fast flying enemies that clip through everything, lots of projectile shooters, lots of bullet sponges)
- The time to change strategies is roughly around whenever you unlock the support fire (attack chopper) ability, after playing for 20 days or so. Keep the base one you first get constantly updated, you won't get a better one prior to level 60. This thing is basically a "kill the boss instantly" button usable twice per level, but it takes a bit of finesse to use right. It goes in the direction you're currently facing so you'll want to make sure your guy is facing and firing at the boss with no distractions nearby or you could waste it.
- So the new strategy that worked for me is centered on leveling Curse to get the ultimate upgrade (Curse and Burn spread to enemies every one second), paired with getting Burn up to the "0.1% chance to restore HP" level (happens way more than you'd think when killing 5k+ enemies per level) and Withering Glare up to the "can cause bullet special effects" level. Also get a little movement speed (though not too much or it gets jerky, I found the initial 20% plus maybe another 10% if nothing better is on offer was sufficient) and basically try to ring enemy mobs and constantly "poison" large amounts of them at once with your cocktail of Freeze, Curse and Burn. Since you're moving so much you don't really need an EXP Bot, dump him and have a Freeze specialist and a Dark specialist in each of the attack and defense slots (the target reticule and shield reticule at the corner of their portrait). The Space Whale is great for dark as it auto-executes enemies that drop below 35% health if they've taken Dark damage in I believe the last 3 seconds, and the green mantis reaper guy is a combo of both Dark and Freeze damage.
- One other possibility is focusing on Light damage (Smite) in combination with Pandy. Pandy has his own set of album cards and if you're keeping up with those you'll get him for free then get at least three upgrades within 30 days for free as well. Then focus on getting the Miniclip (reload) ultimate upgrade so you're constantly reloading and thus triggering Smite all the time
- In terms of gaining power and being able to survive Campaign stages I would say these are the most important things:
> Upgrade your weapon with gold, weapon chips and Tesseracts as needed as much as possible. You don't really need to buy fancy weapons, I did fine with the stock assault rifle the whole way
> Get good robots and get them to their third special attack ability ASAP. This is the easiest thing to screw up as a lot of this is using S chips and you can't undo those once you upgrade like you can with most other stuff. I'm not saying this is the best possible team, but for the strategy I described above, these guys worked well for me: Ullr Dragon, the green mantis guy, the space whale with Dark abilities, and Frost Penguin
> At day 22 or so you unlock Blueprints/Modules. Another good reason to use the Assault Rifle is the first new blueprint you can get is Advanced Assault Rifle from completing Testworks 2-100, which provides a MASSIVE attack boost when filled. The deal with these in general is you equip one at a time, each module piece you put in ups your stats, filling in every square gives you some added special boost. To fill them in just skip most of the crafting and purchase Advanced modules, enough to fill the square in (maybe with crafting them up one level). Then focus on crafting to the final level (single red squares that each provide a very big boost). Make this a priority when it comes available.
> During events, the 60 S chips for robots are probably best to focus on if you're just playing for 30 days (unless a good robot is up as a prize). But the next best is probably red- and yellow-background collectibles with good boosts
> You'll really need to dabble in everything available to gain enough resources and power, however. The game is friendly to F2P but at the tradeoff of a pretty substantial cost of time to be on top of all this stuff.
> For more advanced advice, here's the Reddit account of the guy considered to be the game's top player
