diff --git a/CMakeLists.txt b/CMakeLists.txt
index 90a814e43..1f813d413 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -317,7 +317,16 @@ if(RUN_TESTS)
     SourceT/appfat_test.cpp
     SourceT/automap_test.cpp
     SourceT/control_test.cpp
-    SourceT/cursor_test.cpp)
+    SourceT/cursor_test.cpp
+    SourceT/codec_test.cpp
+    SourceT/dead_test.cpp
+    SourceT/diablo_test.cpp
+    SourceT/doom_test.cpp
+    SourceT/drlg_l1_test.cpp
+    SourceT/drlg_l2_test.cpp
+    SourceT/drlg_l3_test.cpp
+    SourceT/drlg_l4_test.cpp
+    SourceT/effects_test.cpp)
 endif()
 
 add_executable(${BIN_TARGET} WIN32 MACOSX_BUNDLE ${devilutionx_SRCS})
diff --git a/SourceT/codec_test.cpp b/SourceT/codec_test.cpp
new file mode 100644
index 000000000..69631d041
--- /dev/null
+++ b/SourceT/codec_test.cpp
@@ -0,0 +1,10 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Codec, codec_get_encoded_len) {
+	EXPECT_EQ(dvl::codec_get_encoded_len(50), 72);
+}
+
+TEST(Codec, codec_get_encoded_len_eq) {
+	EXPECT_EQ(dvl::codec_get_encoded_len(128), 136);
+}
diff --git a/SourceT/dead_test.cpp b/SourceT/dead_test.cpp
new file mode 100644
index 000000000..5ad255478
--- /dev/null
+++ b/SourceT/dead_test.cpp
@@ -0,0 +1,12 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Dead, AddDead) {
+	dvl::AddDead(21, 48, 8, dvl::DIR_W);
+	EXPECT_EQ(dvl::dDead[21][48], 8 + (dvl::DIR_W << 5));
+}
+
+TEST(Dead, AddDead_OOB) {
+	dvl::AddDead(21, 48, MAXDEAD + 1, dvl::DIR_W);
+	EXPECT_EQ(dvl::dDead[21][48], 0 + (dvl::DIR_W << 5));
+}
diff --git a/SourceT/diablo_test.cpp b/SourceT/diablo_test.cpp
new file mode 100644
index 000000000..7a78a084a
--- /dev/null
+++ b/SourceT/diablo_test.cpp
@@ -0,0 +1,8 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Diablo, diablo_pause_game_unpause) {
+	dvl::PauseMode = 1;
+	dvl::diablo_pause_game();
+	EXPECT_EQ(dvl::PauseMode, 0);
+}
diff --git a/SourceT/doom_test.cpp b/SourceT/doom_test.cpp
new file mode 100644
index 000000000..bf66e4602
--- /dev/null
+++ b/SourceT/doom_test.cpp
@@ -0,0 +1,12 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Doom, doom_get_frame_from_time) {
+	dvl::DoomQuestState = 1200 * 8 + 548;
+	EXPECT_EQ(dvl::doom_get_frame_from_time(), 8);
+}
+
+TEST(Doom, doom_get_frame_from_time_max) {
+	dvl::DoomQuestState = 1200 * 30 + 1;
+	EXPECT_EQ(dvl::doom_get_frame_from_time(), 31);
+}
diff --git a/SourceT/drlg_l1_test.cpp b/SourceT/drlg_l1_test.cpp
new file mode 100644
index 000000000..4419f7b3b
--- /dev/null
+++ b/SourceT/drlg_l1_test.cpp
@@ -0,0 +1,23 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Drlg_l1, DRLG_Init_Globals_4flag) {
+	dvl::lightflag = false;
+	dvl::light4flag = true;
+	dvl::DRLG_Init_Globals();
+	EXPECT_EQ(dvl::dLight[0][0], 3);
+}
+
+TEST(Drlg_l1, DRLG_Init_Globals_noflag) {
+	dvl::lightflag = false;
+	dvl::light4flag = false;
+	dvl::DRLG_Init_Globals();
+	EXPECT_EQ(dvl::dLight[0][0], 15);
+}
+
+TEST(Drlg_l1, DRLG_Init_Globals) {
+	dvl::lightflag = true;
+	dvl::DRLG_Init_Globals();
+	EXPECT_EQ(dvl::dLight[0][0], 0);
+}
+
diff --git a/SourceT/drlg_l2_test.cpp b/SourceT/drlg_l2_test.cpp
new file mode 100644
index 000000000..dc31a2622
--- /dev/null
+++ b/SourceT/drlg_l2_test.cpp
@@ -0,0 +1,8 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Drlg_l2, InitDungeon) {
+	dvl::InitDungeon();
+	EXPECT_EQ(dvl::predungeon[0][0], 32);
+	EXPECT_EQ(dvl::dflags[0][0], 0);
+}
diff --git a/SourceT/drlg_l3_test.cpp b/SourceT/drlg_l3_test.cpp
new file mode 100644
index 000000000..2df876a48
--- /dev/null
+++ b/SourceT/drlg_l3_test.cpp
@@ -0,0 +1,18 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Drlg_l3, AddFenceDoors) {
+	dvl::dungeon[5][5] = 7;
+	dvl::dungeon[5 - 1][5] = 130;
+	dvl::dungeon[5 + 1][5] = 152;
+	dvl::AddFenceDoors();
+	EXPECT_EQ(dvl::dungeon[5][5], 146);
+}
+
+TEST(Drlg_l3, AddFenceDoors_no) {
+	dvl::dungeon[5][5] = 7;
+	dvl::dungeon[5 - 1][5] = 130;
+	dvl::dungeon[5 + 1][5] = 153;
+	dvl::AddFenceDoors();
+	EXPECT_EQ(dvl::dungeon[5][5], 7);
+}
diff --git a/SourceT/drlg_l4_test.cpp b/SourceT/drlg_l4_test.cpp
new file mode 100644
index 000000000..294b3f5ca
--- /dev/null
+++ b/SourceT/drlg_l4_test.cpp
@@ -0,0 +1,16 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Drlg_l4, IsDURWall) {
+	EXPECT_EQ(dvl::IsDURWall(25), true);
+	EXPECT_EQ(dvl::IsDURWall(28), true);
+	EXPECT_EQ(dvl::IsDURWall(23), true);
+	EXPECT_EQ(dvl::IsDURWall(20), false);
+}
+
+TEST(Drlg_l4, IsDLLWall) {
+	EXPECT_EQ(dvl::IsDLLWall(27), true);
+	EXPECT_EQ(dvl::IsDLLWall(26), true);
+	EXPECT_EQ(dvl::IsDLLWall(22), true);
+	EXPECT_EQ(dvl::IsDLLWall(20), false);
+}
diff --git a/SourceT/effects_test.cpp b/SourceT/effects_test.cpp
new file mode 100644
index 000000000..88b5dd6d8
--- /dev/null
+++ b/SourceT/effects_test.cpp
@@ -0,0 +1,52 @@
+#include <gtest/gtest.h>
+#include "devilution.h"
+
+TEST(Drlg_l4, calc_snd_position_center) {
+	dvl::plr[dvl::myplr].WorldX = 50;
+	dvl::plr[dvl::myplr].WorldY = 50;
+	int plVolume = 0;
+	int plPan = 0;
+	EXPECT_EQ(dvl::calc_snd_position(50, 50, &plVolume, &plPan), true);
+	EXPECT_EQ(plVolume, 0);
+	EXPECT_EQ(plPan, 0);
+}
+
+TEST(Drlg_l4, calc_snd_position_near) {
+	dvl::plr[dvl::myplr].WorldX = 50;
+	dvl::plr[dvl::myplr].WorldY = 50;
+	int plVolume = 0;
+	int plPan = 0;
+	EXPECT_EQ(dvl::calc_snd_position(55, 50, &plVolume, &plPan), true);
+	EXPECT_EQ(plVolume, -320);
+	EXPECT_EQ(plPan, 1280);
+}
+
+TEST(Drlg_l4, calc_snd_position_out_of_range) {
+	dvl::plr[dvl::myplr].WorldX = 12;
+	dvl::plr[dvl::myplr].WorldY = 12;
+	int plVolume = 0;
+	int plPan = 0;
+	EXPECT_EQ(dvl::calc_snd_position(112, 112, &plVolume, &plPan), false);
+	ASSERT_GE(plVolume, 6400);
+	EXPECT_EQ(plPan, 0);
+}
+
+TEST(Drlg_l4, calc_snd_position_extream_right) {
+	dvl::plr[dvl::myplr].WorldX = 50;
+	dvl::plr[dvl::myplr].WorldY = 50;
+	int plVolume = 0;
+	int plPan = 0;
+	EXPECT_EQ(dvl::calc_snd_position(76, 50, &plVolume, &plPan), false);
+	EXPECT_EQ(plVolume, 0);
+	EXPECT_GT(plPan, 6400);
+}
+
+TEST(Drlg_l4, calc_snd_position_extream_left) {
+	dvl::plr[dvl::myplr].WorldX = 50;
+	dvl::plr[dvl::myplr].WorldY = 50;
+	int plVolume = 0;
+	int plPan = 0;
+	EXPECT_EQ(dvl::calc_snd_position(24, 50, &plVolume, &plPan), false);
+	EXPECT_EQ(plVolume, 0);
+	EXPECT_LT(plPan, -6400);
+}