When you play Zenith for the first time, it will start with an easy game, at Difficulty level 0. If someone else played it before you, then they might have left it at a difficult setting. To change this:
Start off by having a good look around you: press and hold the left mouse button and drag the mouse. The Sentinel is inactive, so you can take as long as you like looking around. The Sentinel will wake up only if you create or absorb something on the landscape.
What do you see around you? You're looking for your next location: somewhere to place your next synthoid shell. You're also looking for trees to absorb, but don't absorb them until you know where your next location will be, because when you absorb the first tree, the Sentinel will wake up. If you can see the Sentinel, try to see which direction it's looking in: if it's looking away from you, then you know you have some breathing space before it turns to look this way; if it's almost looking at you, then you need to be aware that it might turn to look straight at you in a very short time (or if it turns away, you have the luxury of time).
Don't forget that you can look at the whole landscape from above, using the Map View - press M to see it, and when you're done, press M again to return to the synthoid's view of the landscape.
So by now, you'll be aware of your surroundings. Hopefully the landscape is fairly open, and you can see a way of gaining height in the next few moves agead. You'll know where the Sentinel is, and roughly how quickly you have to move. You'll know where the trees are, and that's your first job: absorb as many trees as you safely can, and then move to the next location.
Keep doing that: look for somehere to move that is higher than your current location, keeping an eye on the Sentinel.
Don't forget that you can place more than one boulder B on a single square, on top of each other, to build a stack. Make sure you have three units of energy available for a synthoid shell, and then place one on top of the stack R. Transfer to the new location by pointing at the stack and pressing Q, and don't forget to absorb your old synthoid shell by pointing at it and absorbing it A.
Have you reached the top yet? :o)
Observe which way Sentinels and Sentries rotate, how often, and by how much. You might see that there is a particularly aggressive Sentinel or Sentry, and change your strategy accordingly. Use the time you have wisely, and be aware that if you stay in one place for too long, it will find you! In later levels, this might not be so easy, and your time might be better spent just climbing, and reacting to a scan when it happens.
Aim to create new Synthoid shells in locations where the Sentinel or Sentries have just scanned, to give as much time as possible before the next relocation is forced. Remember that the Sentinel might have undiscovered friends just about to scan your location.
No point hanging around! You can gain height quickly just using nearby squares, and stacking boulders. Gain height as quickly as possible to get out of a sticky situation quickly. Use all available energy to build stacks of boulders, plus a synthoid. From the new vantage point, it should be possible to absorb the old shell, spy a site for a new shell, transfer to a new synthoid shell, re-absorb the previous stack of boulders, and so on, to seek a new site afresh. Simple! Just avoid the Sentinel though.
Unless you think it's cheating.
Use the height of boulder stacks wisely, and use as few or as many boulders as you need to keep your options open. If you have enough energy to stack 6 boulders, the temptation might be to use them all at once for a quick gain. However, it might be more useful to build a stack of 2 boulders, which saves enough energy to build a stack of 4 boulders in the next stack after that. If you can see ahead two steps, you can plan for what can be seen from the current square, the next square, and the square you plan to occupy after that.
If there's a hill between the Sentinel and some landscape squares, then those squares might be hidden from the Sentinel's view. Keep those squares in mind in case you need a quick refuge. You should be able to wait there until the Sentinel's scan has passed, and take care not to emerge under its stare. Plan your escape from the refuge, because you might not have accounted for all the Sentries, and one might catch you unawares.
In later levels, it can become busy on high ground: lots of Sentries can see you. If you have lots of energy, and it's a bit difficult to avoid the Sentinel and Sentries, then consider leaving a few blocks behind and use the time to gain height instead. The Sentries will be distracted by your blocks, and you'll have more time to move ever upwards.
Nudge up the difficulty if you win (select at the end of the game). If you're heavily defeated a few times, consider playing an easier game the next time. You'll become quicker with experience, and before long, you'll be playing the game into the higher levels, where Zenith becomes an action game, and panic sets in! (and if you go back to the earlier levels, you'll wonder why it was difficult when you first played).
Some games will be very difficult at the beginning, because they offer no way of progressing from the start position, or they are immediately overlooked by a Sentinel or Sentry. Try using the Hyperspace (key H) to jump to another location, where your chances of progression might be better. Take great care when using this from high ground: you'll lose a lot of height, and chances are the land will be barren of trees because you have already absorbed them all, and the Sentries will have scattered them to unreachable parts.
When a Sentinel scans you, don't be caught short. If you're standing on a pile of boulders, and your energy supply falls below 3 units of energy, you have no means to create a new synthoid shell for your escape.
Absorb trees as you go, but only if you have time. If you struggle to achieve the height necessary, try absorbing more trees earlier in the game, to give you energy for the extra boulder you need to gain more height (2 trees = 1 boulder).
Absorb Sentries and Meanies as quickly as possible. There's nothing to lose and lots of energy to gain by absorbing them. Take special care with the Sentries are protected by the scenery. They might be able see you; yet you will not be able to see their square, making them dangerous and difficult to eliminate.
If you start in an open space, then move away as quickly as possible, as the Sentinel's scan is inevitable. The only times you can look around without threat are: (a) at the start of the game, when the Sentinel has not detected your first energy transfer, (b) when the Sentinel and all the Sentries are absorbed, and (c) when you are shielded from the Sentinel and Sentries by the landscape. Note that in the very difficult levels, the landscape begins to flatten out again, but with more Sentries - this is more difficult than the earlier hilly landscapes, because there are fewer places to hide.
Feel like tweaking the game? That's OK - we'd rather you had fun with it than find it too difficult or too easy to play. Use the configuration box — press Esc — to change the Sentry behaviour and the resources available for your game.