Xeno Tactic is similar to Tower Defence, in that you have a bunch of towers (in this case sentry guns) and a bunch of creeps (aka aliens) and you have to stop them getting to the exit or you lose lives.
Sounds simple, doesn't it?
Some things to take into consideration:
The score you die with is the score that goes to the leaderboard, regardless of how well you've done on previous levels. You might get 10,000 on level 5 and only 2,000 on level 6 before you die. The score that goes is 2,000. It sucks, but that's life. If at any point you find yourself above the arcade highscore, sell your turrets and let yourself die! You may not get another chance to be champ
Each level is timed. If you defeat the aliens before the time has ran out you can skip ahead to the next level. This is useful if you're the impatient type (like me). And although the additional seconds are counted next to the score at the top of the screen, it makes NO difference. The time is not added to the score, it's not added to the amount of money you have and basically has no practical use other than to start the next level a bit earlier. If you're upgrading or buying more turrets, don't skip ahead...
Right, time for the tips
Due to time constraints, I'm only gonna give you help on the first level (as if anyone needs it). Later, when I have more time, I'll do the rest of the levels as well
The most common approach is to block off the entrance and force the aliens into a single column, then weave a maze through the level so that they are kept close to an almost constant stream of turrets that kill them long before the end of the maze
This approach does work. Most of the time. Flying aliens are an exception. There are two tactics to face this. Have vulcan turrets lined up in the flight path of the flying baddies, or get the dedicated DCA (anti flying) turret.
Map One
Right, so, first thing. Block off the entrance (where the aliens enter) with vulcan turrets. The last turret will need to be one block away from the entrance or it won't go down as you will be 'blocking' the aliens.
Place another couple of turrets starting from the top of the map and head straight down. You only need two or three. Put in place an SAM turret. These are powerful beasts that upgrade nicely
For the first few levels that should do it
At the end of level 3 / start of level 4, upgrade the SAM turret. For level 6, put in a couple of vulcan turrets and upgrade the SAM again.
Level 8 and 13 is a boss. You won't be able to kill him on the first pass. Once he's started down the column of turrets towards the exit, sell the turret at the top and get ready to put a vulcan turret at the exit. When he gets there, buy the turret, blocking his path. The boss will turn around and make his way back up the column. As soon as he turns around, sell the turret and get ready to buy another one at the top of the column of turrets (back in place of the first one you sold). This little manouver can keep a baddy going in circles in your maze. The draw back is timing. If the next wave of baddies comes, they'll go for the closest exit. The boss should die on it's way back up the column.
Now it's just a case of common sense to upgrade the turrets as you see fit. Place a DCA turret in the middle of the map behind your SAM turrets before level 14.
A list of what baddies spawn on what level is to come
Happy gaming