Your opponents bases are
In Play so
Stealth Tower can copy them too.
Stealth Tower copies a base, it remains a copy of that base regardless of what happens to the original (destroyed or returned to hand, etc).
This relies on an understanding of what "In Play" means in the context of this game.
A Player Turn consists of three phases: Main, Discard and Draw.
1) Main Phase
At any time during your Main Phase you may perform any of the
following actions, in any order you wish.
- Play cards from your hand
- Use the Primary Abilities of in-play Bases
- Use the Ally/Scrap abilities of in-play Ships and Bases
- Use Trade to acquire new cards from the Trade Row
- Use Combat to attack an opponent and/or their Bases
Playing Cards: There is no cost to play a card, simply place it
in-play (face-up on the table in front of you [the active player]).
There are two types of cards you can have in your deck: Ships and
Bases: Unlike Ships, Bases are not discarded at the end of the turn.
Instead, they remain
in-play until they are destroyed or scrapped.
2) Discard Phase
- Lose any Trade remaining in your Trade Pool
- Lose any Combat remaining in your Combat Pool
- Put all
in-play Ships into your Discard Pile [and leave all Bases in-play]
- Put any cards left in your hand into your Discard Pile
3) Draw Phase
Draw five cards, then your turn ends
In the Main Phase the first action says you can play cards from your hand. Playing a card involves putting the card from your hand
in-play in front of you. During the Discard Phase all
in-play Ships are discarded, but Bases (and Outposts, which are Bases) remain
in-play. Therefore Bases Played by any player are
in-play, even after their turn ends.