Nightfall: Kingdom Frontier TD

I opened Nightfall: Kingdom Frontier TD because the cover art looked like a cozy fairy-tale tower defense, and for the first ten minutes that's exactly what it was. A tiny king runs around a green, grassy island, puts up a castle whenever he finds an empty plot, and when night falls and monsters creep in, the soldiers inside the walls shoot back on their own.

By the second night, things had changed. The screen flashed a warning that the castle was under attack, while my king was still standing at the far end of the island. I lost that battle at wave two of five, got a consolation prize of exactly one hundred gold, and replaying it cost another five stamina.

How a night in the ruined citadel plays out

Every stage is split into two overlapping phases, day and night, and it's over after five rounds. During the day, a sun at the top of the screen shows how many waves are coming. Your hands are free to roam the island, spending silver on houses and defenses.

Tap the Battle button and night falls at once, then monsters march in from the edge of the forest along a fixed path, and you can already see their lineup in the right corner of the screen. The fighting is completely automatic, with the king and his soldiers targeting whatever is closest.

Your job is just to run to the spot under pressure and tap the round skill button in the bottom corner. Clear the wave and day breaks again, along with a bonus of silver based on your current daily income. If the castle runs out of health, though, the stage ends right there, with no second chance.

What I like about this rhythm is that it's short and tidy. A five-wave stage only takes a few minutes, so losing doesn't feel like wasted time. There's also a speed-up button right next to the wave clock, and one tap makes those long stretches of monsters walking go by much faster.

The king walks on his own, and you have to step right onto the building plots

This is the detail that will trip up a lot of people in the first ten minutes. The buildable plots sit right in the world, not on any toolbar. You have to walk your king squarely onto the glowing stone before the build menu pops up.

Stand half a tile off and nothing happens, and tapping the plot with your finger doesn't work either. The first few times I thought the game had frozen. Once you get the hang of it, though, it turns out to be rather satisfying, because it feels like you're really out surveying the land rather than tapping a card.

The build menu comes with a small ring around the plot that lets you switch between the building types you've unlocked. The castle is mandatory and has to go up first; it costs three silver and has a hundred health and twelve damage. Upgrade it to tier two and it gets three hundred health, and tier three brings seven hundred.

Houses are cheaper at two silver each, and every night each one produces an extra silver. They're what you'll want to build early if you plan to play the long game in later stages. The default income is three silver per day, and that number is the spending ceiling for the whole stage.

Silver doesn't carry over from one battle to the next. In other words, every stage is its own separate round with its own budget. What really builds up over time lives outside the battles.

Outside battle there's a research tree and a row of locked slots

Leave a stage and you're back on a map drawn on a scroll, where the game calls each region a chapter. I was in chapter one, a ruined citadel, while chapter two, a dark forest, was still pitch black and waiting to open.

Every stage in a chapter has three difficulty levels side by side; normal is open from the start and the other two are locked. Next to them is a box listing the tricky conditions that will apply to the battle, and a button that triples the rewards, which is locked too. That layout makes it clear the game wants you to replay each stage several times.

The main place to spend gold is the research tree, opened with the Research button at the bottom edge of the screen. The first node I unlocked cost fifty gold and added knight barracks, one more building type allowed in battle. A new account has exactly one hundred gold, so that node ate half of it right away.

The whole tree stretches far down with dozens of branches still grayed out. One glance tells you this is where the gold really goes. The row of buttons at the very bottom of the screen also has five more padlocked slots: Cards, Inventory, Pets, Civilization and Guild.

They open gradually as your chapters progress and can't be bought, so in your first session the only two things you can really tap are the shop and the research tree.

Five stamina a battle, and here's where the game hands you the bill

Every time you enter a stage you lose five stamina, and the stamina bar is full at thirty, which works out to six runs before you sit and wait. And the waiting is real, with the refill timer ticking back one point at a time.

A loss costs the same five points as a win, yet a loss only pays a hundred gold while a win pays a thousand gold plus a star, so a botched battle comes at a steep price.

Gems are the currency above gold, and the official way to get them is the shop. The gem tab lays out six tiers from one hundred sixty up to fourteen thousand. Every tier carries an extra line promising double gems on the first purchase, so each tier is worth twice as much the first time you buy it.

The special packs tab is where the most expensive stuff lives. There you'll find a no-ads pack, a monthly card, and a monthly perk that gives six hundred gems up front plus one hundred sixty gems and thirty stamina every day. At the top sits the permanent perk: three thousand gems up front plus four hundred a day, a stamina cap raised to fifty and twenty percent more rewards.

As for what gems are for, the daily shop answers very bluntly: thirty stamina for a hundred gems, refreshing every seventeen hours. On the US Google Play store, the game's purchases run from $0.99 up to $194.99 per item, and that ceiling says a lot about who the publisher is aiming at.

The mod opens exactly that shop

The Nightfall: Kingdom Frontier TD mod in VipMod has exactly one switch, called Free pack purchases. It lives inside the floating red octagon MOD button on the left edge of the screen. Turn it on, tap the restart button right in that panel, and wait for the game to come back up, and that's it.

After that, just open the shop and buy any card you like. What I like is that it doesn't pump random numbers into your wallet. It runs exactly the code the game runs after a successful payment, so what you get is exactly what the card says.

I tested seven different packs, not just one. The smallest gem pack paid out three hundred twenty gems instead of one hundred sixty, because the first-purchase bonus still counted, while the biggest pack jumped straight to twenty-eight thousand.

The no-ads pack came with a thousand gems, and the monthly card came with twelve keys and a countdown of exactly thirty days. The monthly perk paid seven hundred sixty gems plus thirty stamina, and the permanent perk got stamped as purchased and lifted the stamina cap from thirty to fifty on the spot.

The proof I found most convincing wasn't the number at the top of the screen. After I received the double-gold pack, the reward listed on the stage one selection panel jumped from one thousand to two thousand gold, and the battle I lost right after paid two hundred gold instead of one hundred.

I also tested spending the gems by buying thirty stamina for a hundred gems in the daily shop, and the stamina arrived at once. Then I turned the mod switch off completely and reopened the game from scratch, and the gems, the fifty-point stamina cap and the cards stamped as purchased were all still there.

A few things worth knowing up front, so you don't expect the wrong thing:

• Every card in the shop shows a coming-soon line instead of a price and looks exactly like a dead button, but tapping it still delivers the goods normally.
• I couldn't test the guild packs, because guilds are among the features still locked early in the game.
• The chapter packs tab is completely empty while you're still in chapter one, so there's nothing to tap there yet.
• This switch needs a game restart to take effect; turning it on midway and heading straight into the shop does nothing.

How it plays for real

The visuals are the clearest strength. The grass is lush and green, the characters are round and cute, and the moment the sky shifts from gold to deep blue as night falls lands nicely. The day-night loop is also so easy to grasp that you don't need to read anything, two stages teach you everything, yet there's still room to weigh whether to build silver-earning houses or roadblocks first.

I have two complaints. First, the building plots are hard to line up with, as described above, and standing a little off means the menu won't open. Second, more than half the buttons on the main screen are padlocked from the start, which makes the first session feel a bit empty next to what the promo images promise.

Another big plus is that it plays with the network switched off completely. I turned on airplane mode and went back in, my old data was intact, and I could still build the castle and fight through every wave as normal.

On Google Play the game holds 4.4 stars from more than 78,000 reviews and has passed a million downloads.

So who should play it

If you like gentle tower defense, a few minutes per round, no fast reflexes needed but still room to plan where your silver goes, this is a very easy game to get into. It suits broken-up sessions, like waiting for someone or taking a break, because quitting mid-battle costs you little more than five stamina.

And if you downloaded it before and gave up because the stamina bar ran out far too fast, the mod hits exactly that spot. After I claimed the permanent perk, my stamina cap rose to fifty and every battle paid extra rewards, so the wait for stamina to refill all but disappeared from my sessions.