Once you've finished the intro and are fully dropped into the world of aliscans with a goal : build a tower of 5000n. You may notice that there are many different spots to build towers (which are marked by pillars of white light you can see in the distance) but as long as you get a single one to 5000n you will have beat the "main" objective of the game. You might then be tempted to speedrun and go all in on one of the lower level towers and ignore the rest, but I'd advise against it. Firstly because why would you want to ignore most of the game you paid money for? And also because getting other towers to a certain threshold (usually 1000n, some 2000n and only one which requires an extraordinary 4000n but we'll get to that later) unlocks the game's "sidequests" with other characters which provide breaks from the gameplay and upgrades for your character.

Burggeist is an open world game with towers which can in theory be tackled in any order, but as you might expect areas closest to your starting base of Fort Orifice (don't laugh) are easiest. With that said, there are no overworld enemies, feel free to explore the entire world, there are items and secrets to find everywhere from the get go. If you find any polyhedrons, feel free to break them, though your starting character will likely only be able to break the smaller triangle polyhedrons until you've upgraded your gyromantia and burggeist armaments

All that said, my recommendations are to head to the closest tower in Champ Frontiere, slightly northeast from Fort Orifice and reach level 1000n. I find the best way to achieve this is to leave burggeist near the tower bombarding the area inmediately facing where enemies are coming from (they only ever come from one general direction at a time in most towers) and use the high ground walls around the tower to divebomb off into the enemies using the fireball gyromantia. This takes advantage of the height influence, acrobat and base damage attributes of your character to stack some decent damage multipliers which will grow over time. Take care of not overusing this as you're pretty useless without gyromantia resources, these can be regenerated quickly at angel statues so before each fight be sure to find the nearest ones and make a mental note of where they are so you can use them in battle. After each construction you can upgrade the tower's defences using heretic lime, the game's currency, though beware that if the tower collapses the upgrades will go down by a level. Once you have reached 1000n you will be able to talk to your first character and do their little quest. If you're ever lost on what that entails, the "Map and Comms" section will include the quests and their requirements. Once you have done said quest you will have unlocked a very useful gyromantia called lime coat, which lets you give more defences to your tower. Very useful for the tougher challenges of the game. You will also have unlocked some gyromantia tokens, which are used to upgrade your gyromantias. Go to Ignace -> Gyromantia -> Customize. I recommend spending whichever tokens you have on fireball first.

After doing all this, I recommend not building this particular tower more, but going to the merchant at Fort Orifice and buying the flame torus gyromantia (a glider which can be comboed with other movement abilities to get around). Trying to get up the spiral tower near the tower you've built to get a nice item and then going north east to the forest and building said tower, as the sidequest you can unlock there at 1000n leads to getting a really nice gyromantia called Witch's Broom, which lets you go up vertically. Comboing this with fireball makes for very nice synergy as you gain height to then divebomb down and do massive damage.

If you do all this, you should have enough of an idea of how to proceed through the rest of the game. Use your experience points to upgrade your abilities (spike wall is very useful, so are acrobat, height influence and tower autorepair). And just generally have a great time traversing the world and fighting the abhorers

There's several of them, with varying difficulties of both terrain and numbers. Scouting the terrain ahead of time to try and identify the best high vantage points and likely choke points for adequate defence is very much recommended. Tower difficulties go up with building level, but some towers have higher or lower "base levels" than others. The easiest way to see is to get close to a tower, the HUD should show the building level, the durability (the number at the top next to the tower icon) and a enemy wave level (the two clashing swords). Generally speaking early game you should not be doing towers that start at higher than 12 or so. The hardest tower in the game starts at a whopping 50 level and reaches around 100 by the time you complete it. Its the greatest challenge, but reaching 4000n in said tower unlocks a sidequest which gives access to the best weapon in the entire game

These confused me at first, Im still not entirely sure if they have a different purpose, but they generally hold items at the top. Most will require skillfull use of traversal powers to get there. Generally speaking the easiest way is to find the tallest nearby structure you can climb and combo movement powers to get there. The hardest of these is in the western part of the map. There is a white rock structure which if you do the following sequence at the very top from, can get you up the tower (with upgraded gyromantia)sprint + witch's broom + jump + witch's broom + lightning dash forward and upward 2 times + flame torus.

These have expansions for the Burggeist's foundation he carries around and essentially let you fit more weaponry on top of it, very much worth it, though some may be a bit tricky without flame torus and witch's broom.

These give Heretic Lime (currency used to upgrade burggeist and buy stuff), the more faces the polyhedron have the harder they are but the more lime they provide. White Polyhedrons are DPS checks, i.e do above a certain amount of damage to break em (put the burggeist right next to the polyhedron and open fire on it, remembering to either target the polyhedron directly or narrow its field of attack as much as possible to concentrate firepower. Purple Polyhedrons require burst damage from a gyromantia i.e a single strong attack. There are many ways to achieve high damage but I like jumping off from a nearby high ground and divebombing onto them for maximum height + acrobat damage.

Some burggeist armaments are just sitting in the overworld, the first youre likely to come across is near the forest to the north east of the starting area. There is also another one in the forest east of the starting area, but early game you are unlikely to have enough damage potential to break em. Id focus on height difference + acrobat and base damage if you really want to rush them, but upgrading the starting artillery is also a very worthwhile investment

Sheep give heretic lime, they are similar to Koroks from Zelda Breath of the Wild. Essentially when touched they fly up somewhere, and if touched afterwards will burst and give the player Heretic Lime

Most achievements are fairly self explanatory. Any achievement that mentions the name of a character requires doing that character's quest. Every tower in the game has a quest associated with it, and requires reaching 1000n or 2000n to reach except for the tower in Salina Porporossa which requires reaching 4000n and unlocks the best armament in the game. Most other achievements involve doing something a bunch of times like touching sheep, finding all the items scattered across the map, getting 1092 total experience points etc.

The only one that requires explanation is the one for defeating the "true" final boss of the game Axiom. This requires going to Margrave tower in the north west of the map and doing the quest associated with it. In order to do this quest you have to do the quest in the tower built on top of a hill lookind down at a "book tower" in the forest at the southwest of the map. Once that quest is finished, go back to the margrave tower and you'll unlock an achievement as well as being able to challenge the final boss when you return to Fort Orifice after building a 5000n tall tower.

During tower defence sections, trumpeters will show up, buffing enemies and making the completion of a construction impossible. The challenge lies in that they are far away usually and the tower's defence will have to be left to Burggeist whilst you go and destroy the trumpeter. Generally when this happens I park Burggeist close to the tower and have him bombard the area closest to it, making sure as many possible enemies get attacked before reaching the tower whilst I quickly race to kill the trumpeter. Leaving a few Fuze Aerosol Mines to shore up defences, applying Lime Coat to the tower or setting up a portal for a quick return are all viable strategies to help with this.

At a certain point, at 2000-3000n a boss trumpeter will appear with a boss health bar. They can be quite tricky, but I prefer to let them get close before sending the burggeist to concentrate fire on it. After a certain threshold they'll get knocked down, setting themselves up for a strong attack by the player on to it, just be careful that the other enemies dont destroy the tower if you leave it undefended

The final boss trumpeter appears when your tower gets close to 5000n and must be defeated to complete the construction. The main difficulty is less the boss itself and more having to leave the Burggeist in charge of defending from what are likely large numbers of enemies whilst you deal with the Trumpeter, as well as the gyromantia resources which will likely have to be refilled near an angel statue in between bouts. Dont be afraid to go back and help out the burggeist in between attacking the trumpeter, its better to save the tower and have to attack again later than to overcommitt and lose all progress. If you did the quest for the baroness though, you will have access to the sword of boro jemma and thus burggeist should make quick work of the boss.

Axiom

This boss sucks, I have to be honest with you. Using different mechanics from the rest of the game is already annoying enough but the execution is spotty too. Basically, you have to hit it to build up some abhorrence and dodge its attacks (dodge + side to dodge vertical swipes and just dodge to dodge horizontal swipes) so you can then hit dodge + attack at the same time with abhorrence in you to parry its attack like the green vertical swipe for example at the correct timing which will remove like a third of its health. Conversely you can just hit him for like an hour, you cant actually die, but the other method is a lot faster.