21. Being Drunk when the falling of rocks end will give you a big bonus!

Explanation
Completing a Meteor Storm in Drunk Mode will give you an additional bonus.

How?
Successfully completing this secret will give you the secret. (Thisa also unlocks the 1st GOD BADGE but only with 100% Speed).

22. Getting rid of all shooting aliens not using a single bullet will give you extra weapons to use!

Explanation
Complete an entire level using only a SCOOP. This only works in levels where aliens shoot at you (not in bonus level). If you do so you will be awarded 10 rockets! If you already have the maximum of 50 Rockets, you'll be given 50,000 points instead!

How?
Just make sure you have a Scoop when a level where the aliens swoop down low in the beginning (like Level 2 or Level 6 for example).

23. Find X birds on grid will give you Xx beans limits!

Explanation
Finding 10 Birds in the Memory Station will increase the maximum allowed money you can hold to 999,990 credits (10 times more), instead of 99,990.

How?
This can take awhile. Just keep searching. (Collecting the maximum 999,990 credits and dying with that much in your account will give you the 6th GOD BADGE).

24. Passing the LC with CCM will open up a quiet lock!

Explanation
If you have at least 200,000,000 (CCM) points when you complete Level 100 (LC) you will be given a SECRET COUNTER (little silver number on your STATUS BAR). This is a little counter that will show how many secrets you've unlocked in your current game and will show up in every game afterwards.

How?
Get as many x5 Bonuses as possible. In Memory Station it is best to collect the x5-pair at the end. Complete as many Meteorstorm preferably with x5 and Max. Speed (achieve the Mega Meteor Storm Bonus by completing the Meteor Storm with full of speed without slowing down once). Get perfects in all the Bonus Levels preferably with x5. Complete the "Big Trouble" bosses with a multiplier especially the final boss (Level 100) preferably with x5. Skulls CAN help if you are lucky and get 3x GREEN, 3x BLUE (buy time with money to last x5 longer) and 1xGREEN+BLUE+RED for more Time, Speed (good for Meteor Storm to be quick enough) and Bullets.

25. The clearing of the non shooting aliens, will give you larger points the next time you do the same.

Explanation
Getting PERFECT on Bonus Levels in a row will give you bigger and bigger bonuses (10,000 / 25,000 / 50,000 / 100,000 / 250,000 / 500,000 / 1,000,000 / 2,500,000 / 5,000,000 / 10,000,000 (from this point always 10M)).

If you fail to get a PERFECT on a level though, the next one will only give you 10,000 points again.

How?
Just play through 10 Bonus Levels in a row without missing a single alien! Collecting Meteor Storm, Memory Station, Gem Bomb and Money Bomb ALWAYS gives you PERFECT Bonus (increase your chance for one of this extras by collecting question marks).

26. Collecting K gems will bring you the most valued gem drop!

Explanation
Collecting 100 gems will give you a GEM DROP level. Doing this 10 times (and thus collecting 1,000 gems) will give you a SUPER GEM DROP level where the diamonds are worth millions of points each (instead of the thousands of points)!

RED GEM: 1,000,000 Points!

PURPLE GEM: 5,000,000 Points!

GREEN GEM: 10,000,000 Points!

How?
Just play for a VERY long time! Make sure the Gem Counter is on and just keep trying to collect those gems (especially from Gem Bombs) until you reach 1,000 (the counter will reset back to '000') once you do. A VERY difficult secret to complete!

27. A lower rank will be given when fastest marker is taken!

Explanation
You have to collect the DARK PURPLE RANK which demoted you a rank. To unlock this Secret Rank buy a Rank in the Shop when you already own all 6 (see Secret 14).

How?
Collect all 6 RANK MARKERS (by any means) and then buy a 7th in the Shop. Your greed will be rewarded by unlocking the Dark Purple Rank Marker! It will fall randomly at any point from now on so just keep collecting every RANK MARKER that drops and eventually it should be a Dark Purple one (they move very fast, so be ready!).

28. The cleaning of XIIxII non shooting alien attackers waves will give you a high promotion.

Explanation
Completing 24 Bonus Levels (XIIxII = 12 x 2) with PERFECT scores IN A ROW in one game will unlock CHAMPION RANK for every game!
How?
You need good weapons and preferable Super Auto Fire. Every 100 Levels aliens appear mirrowed on screen. Try to collect Meteor Storm, Memory Station, Gem Bomb and Money Bomb as they give you ALWAYS PERFECT Bonus. Level 49 and 99 are the worst, try to keep Scoop Aliens with you.

29. Ei Xmo Tymo Rollu Alehyo Ad Rew Tera Xolly Eathui!

Explanation
Collect E-X-T-R-A in order for 5,000,000 points!

NOTE: You cannot collect more than one of each letter and any collected in a MEMORY STATION will not count and will thus ruin your attempt at collecting this bonus.

How?
Just be very careful to collect the letter you want. Avoid '?' Icons as they could be the wrong letter or a duplicate of one you already have. Avoid Memory Stations or be careful not to collect any letters.

30. Ei Xmo Tymo Rollu Alehyo Ad Rew Tera Xolly Eathui!

Explanation
Collect A-R-T-X-E in order for 5,000,000 points!

NOTE: If you already have four lives and both armour in place when you collect this you'll get an additional 'SUPER' bonus of 1,000,000 points!

How?
The same as Secret 29: Just be very careful to collect the letter you want. Avoid '?' Icons as they could be the wrong letter or a duplicate of one you already have. Avoid Memory Stations or be careful not to collect any letters.

Source: warblade.fandom.com