Short-Lived is a difficult Special Mission in BTD5. It is unlocked at Rank 60 (40 in Bloons TD 5 Mobile) to play it, making it the final Special Mission unlocked. 1,000 and 100 are awarded upon completion. The player has to beat Monkey Lane, Medium - but towers and agents will only last 10 rounds. The money reward for completing a round is increased to 299 plus the round number.
Tips
This has only been tested in BTD5 Mobile so far, but the player can save and exit the game, resume the game, and every tower's "levels remaining counter" (located where the sell button would normally be) is reset to 10, this has since been fixed on iOS.
Banana Investments Advisories disappear before the interest for the 10th round is being paid. However, the price of $15,200 without Path 1 upgrades is still less than the maximum earnings of $21,995. To achieve maximum earnings collect the balance after 8 rounds as well as during the 10th round.
The player must not buy a Temple of the Monkey God early in the game, because the player would lose it in the early rounds. Buy it at round 56.
Bloonsday Device Pros are very good for later rounds (since the B-Day Device costs 250).
If you buy 2 of this and do the mission during a double Monkey Money day, The reward is 1500.
2|3 Dart Monkeys are the cheapest and the best camo detection for early rounds and large groups of bloons that each dart in each volley can get while 1 or 2 Juggernauts set to "last" and placed at the end of the first stretch of track in later rounds help a lot against ceramics and camo leads.
Monkey Tycoon is useless as you are unable to sell your towers.
Save your money and try to survive with minimum towers needed until you get to Round 56 (if you build a tower during or before Round 55, it will disappear before Round 65).
The best time to beat this mission is when double Monkey Money is in effect as the player gets 2000.
Prior to version 1.6., there was a bug on the iOS version that if the player exits and then loads the save, every Tower will have their lifespans reset to 10 rounds again, making the difficulty of this Special Mission considerably easy, as long as the player knows the current lifespans of Towers.
In Bloons Tower Defense 5 HD, the player can sell a tower before it disappears, but it doesn't show the countdown, so it's difficult to tell which round to sell it. Also, it doesn't give 299+round end reward, which makes the special even more difficult.
When the timer reaches zero for a tower, a high-pitched "pehng" sound appears and the tower vanishes in a way where the tower "shrinks" by having squares of the sprite wipe into smaller and smaller squares inwards.
However on mobile, towers does their sell animation instead.
1,000 and 
100 are awarded upon completion. The player has to beat Monkey Lane, Medium - but towers and agents will only last 10 rounds. The money reward for completing a round is increased to 299 plus the round number.
1500.